| 0/0 |
2026/05/17 04:49 |
flow |
assessment-security |
43m
Results: map[DenialOfService:true Explanation:The bug is a memory and resource leak in the core DVB demux subsystem
(`drivers/media/dvb-core/dmxdev.c`), which can be triggered by an unprivileged
user with access to the DVB demux device node (typically
`/dev/dvb/adapterX/demuxY`).
### Root Cause Analysis
The vulnerability occurs when starting a PES filter that has multiple PIDs
(feeds) attached to it.
1. The user configures a PES filter using the `DMX_SET_PES_FILTER` ioctl, which
adds the first PID to the filter's feed list.
2. The user adds a second PID to the same filter using the `DMX_ADD_PID` ioctl.
3. The user starts the filter using the `DMX_START` ioctl, which invokes
`dvb_dmxdev_filter_start()`.
4. `dvb_dmxdev_filter_start()` iterates over the filter's feed list and calls
`dvb_dmxdev_start_feed()` for each feed.
5. The first feed starts successfully, allocating underlying driver resources
(in this bug report, `vidtv_mux` and its associated structures).
6. The second feed fails to start (e.g., `dmx_ts_feed_set()` returns `-EINVAL`
because the `pes_type` is already in use by the first feed).
7. Upon failure, `dvb_dmxdev_filter_start()` attempts to clean up by calling
`dvb_dmxdev_filter_stop()`.
8. **The Bug:** `dvb_dmxdev_filter_stop()` contains a check `if
(dmxdevfilter->state < DMXDEV_STATE_GO) return 0;`. Because
`dvb_dmxdev_filter_start()` only updates the state to `DMXDEV_STATE_GO` at the
very end of the function (upon complete success), the state is still
`DMXDEV_STATE_SET`. Thus, `dvb_dmxdev_filter_stop()` returns immediately without
stopping the first feed.
9. The first feed is left running indefinitely. Even when the file descriptor is
closed, `dvb_dmxdev_filter_free()` calls `dvb_dmxdev_filter_stop()`, which again
does nothing. The filter is reset and its `dmxdev_feed` structs are freed, but
the underlying `dmx_ts_feed` and the hardware/driver resources are permanently
leaked.
### Security Impact
- **Denial of Service (DoS):** An attacker can repeatedly trigger this bug to
leak `dmx_ts_feed` slots and underlying driver memory (like `vidtv_mux` buffers
and structures). This will eventually exhaust the limited number of demux feeds
or system memory, leading to a Denial of Service (OOM).
- **Cross-Process Data Leak/Corruption:** Because the leaked feed continues to
run and holds a pointer to the freed filter slot, if another process opens the
demux device and reuses the same filter slot, the leaked feed will start writing
its TS packets into the new process's buffers.
- **Exploitable:** There is no memory corruption (Use-After-Free) in the kernel
itself because the buffer pointers are properly locked and checked before
writing, and the filter struct itself is not freed (it's part of a pre-allocated
array in the `dmxdev`). Thus, it is not exploitable for privilege escalation.
- **Unprivileged Access:** The `/dev/dvb/adapterX/demuxY` device nodes are
typically accessible to unprivileged users (e.g., users in the `video` group or
the active desktop user via ACLs). Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:true UserNamespace:false VMGuestTrigger:false VMHostTrigger:false]
|
| 1/1 |
2026/05/17 04:49 |
action |
syz-repro-to-c-repro |
0m
Results: map[SimplifiedCRepro:// autogenerated by syzkaller (https://github.com/google/syzkaller)
#define _GNU_SOURCE
#include <endian.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
static long syz_open_dev(volatile long a0, volatile long a1, volatile long a2)
{
if (a0 == 0xc || a0 == 0xb) {
char buf[128];
sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block", (uint8_t)a1, (uint8_t)a2);
return open(buf, O_RDWR, 0);
} else {
unsigned long nb = a1;
char buf[1024];
char* hash;
strncpy(buf, (char*)a0, sizeof(buf) - 1);
buf[sizeof(buf) - 1] = 0;
while ((hash = strchr(buf, '#'))) {
*hash = '0' + (char)(nb % 10);
nb /= 10;
}
return open(buf, a2 & ~O_CREAT, 0);
}
}
uint64_t r[1] = {0xffffffffffffffff};
int main(void)
{
syscall(__NR_mmap, /*addr=*/0x1ffffffff000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x200000000000ul, /*len=*/0x1000000ul, /*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/7ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x200001000000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
const char* reason;
(void)reason;
intptr_t res = 0;
if (write(1, "executing program\n", sizeof("executing program\n") - 1)) {}
// syz_open_dev$dvb_demux arguments: [
// dev: ptr[in, buffer] {
// buffer: {2f 64 65 76 2f 64 76 62 2f 61 64 61 70 74 65 72 23 2f 64 65 6d 75 78 23 00} (length 0x19)
// }
// id: intptr = 0x0 (8 bytes)
// flags: open_flags = 0x20000 (8 bytes)
// ]
// returns fd_dvb_demux
memcpy((void*)0x200000000080, "/dev/dvb/adapter#/demux#\000", 25);
res = -1;
res = syz_open_dev(/*dev=*/0x200000000080, /*id=*/0, /*flags=O_NOFOLLOW*/0x20000);
if (res != -1)
r[0] = res;
// ioctl$DVB_DEMUX_DMX_SET_PES_FILTER arguments: [
// fd: fd_dvb_demux (resource)
// cmd: const = 0x40146f2c (4 bytes)
// arg: ptr[in, dmx_pes_filter_params] {
// dmx_pes_filter_params {
// pid: int16 = 0xfff (2 bytes)
// pad = 0x0 (2 bytes)
// input: dmx_input = 0x0 (4 bytes)
// output: dmx_output = 0x3 (4 bytes)
// pes_type: dmx_ts_pes = 0x5 (4 bytes)
// flags: dmx_pes_filter_flags = 0x4 (4 bytes)
// }
// }
// ]
*(uint16_t*)0x200000000000 = 0xfff;
*(uint32_t*)0x200000000004 = 0;
*(uint32_t*)0x200000000008 = 3;
*(uint32_t*)0x20000000000c = 5;
*(uint32_t*)0x200000000010 = 4;
syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0x40146f2c, /*arg=*/0x200000000000ul);
// ioctl$DVB_DEMUX_DMX_ADD_PID arguments: [
// fd: fd_dvb_demux (resource)
// cmd: const = 0x40026f33 (4 bytes)
// arg: ptr[in, int16] {
// int16 = 0x7 (2 bytes)
// }
// ]
*(uint16_t*)0x2000000000c0 = 7;
syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0x40026f33, /*arg=*/0x2000000000c0ul);
// ioctl$DVB_DEMUX_DMX_START arguments: [
// fd: fd_dvb_demux (resource)
// cmd: const = 0x6f29 (4 bytes)
// ]
syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0x6f29, 0);
return 0;
}
]
|
| 2/1 |
2026/05/17 04:49 |
action |
kernel-checkouter |
1m
Results: map[KernelSrc:/app/workdir/cache/src/cbaf504c902d4927ef09b1a63649f6541765210c]
|
| 3/1 |
2026/05/17 04:50 |
action |
kernel-builder |
21m
Results: map[KernelObj:/app/workdir/cache/build/1f4c642d915d7d0d41fa6593ea78ee5f17bfebae]
|
| 4/1 |
2026/05/17 05:12 |
action |
codesearch-prepare |
12m
Results: map[Index:codesearch-index]
|
| 5/1 |
2026/05/17 05:24 |
agent |
expert |
8m
Model:
Results: map[DenialOfService:true Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:true UserNamespace:false VMGuestTrigger:false VMHostTrigger:false]
Instruction:
You are an experienced Linux kernel security engineer. Your task is to analyze given kernel bug report
and determine its security impact based on the following dimensions.
Use the provided tools to examine the source code, check for capability checks (e.g., capable(), ns_capable()),
and understand the nature of the bug. Analyze the given kernel build and configuration.
You can check the kernel config by grepping ".config" file; you can check kernel cmdline by greeping
".config" file for "CONFIG_CMDLINE=". Assume sysctl parameters have default values.
But analyze for the corresponding production build w/o debugging tools enabled (like KASAN, KMSAN, UBSAN).
Don't make assumptions; verify them with source code access. Try different strategies when analyzing the bug:
- think of ways in which the vulnerable code is unreachable
- or the other way around: try to come up with different ideas of how an unprivileged user can reach the bug
If still unsure err on the side of the bug being non-exploitable/not-accessible.
In the final reply, provide a reasoning for your assessment.
Analysis dimensions:
* Exploitable:
Determine if the bug can result in memory corruption or elevated privileges.
Memory safety issues are almost always exploitable (KASAN or UBSAN reports for use-after-free, out-of-bounds;
refcounting issues, corrupted lists, etc). When kernel is crashing on a completly wild pointer access
(e.g. user-space address, or non-canonical address, but not on NULL or address corresponding to KASAN shadow
for NULL address), including both data accesses and control tranfers, that's also usually implies possibility
of exploitation. Such reports usually say "unable to handle kernel paging request".
Uses of uninitialized values detected by KMSAN may be exploitable b/c attacker frequently can affect uninit
values with spraying techniques. However, for these exploitabability depends on how exactly the uninit value
is used in the code, and what it affects.
Think of what happens after the bug is triggered. Some bugs cause kernel panic and halt execution,
they are harder to exploit. For example, BUG reports halts the kernel. However, WARNING reports don't halt
execution in production builds. Debug bug detection tools (like KASAN, KMSAN, KCSAN, UBSAN) are also not enabled
in production builds, so attacker can freely exploit these bugs w/o being detected by these tools.
If you see an integer overflow, think how the overflowed value used later (if it's used as allocation size,
or an array index). If you see an out-of-bounds read, think if it's followed by an out-of-bounds write as well.
Some KCSAN data-races may be exploitable by skilled attackers as well. Think what data structures got corrupted
as the result of data races and how. However, note that kernel has lots of "benign" data races that don't lead
to any runtime misbehavior at all.
* Denial Of Service:
Determine if the bug can result in denial-of-service. Most bugs can, since they cause system crash,
hangs, deadlocks, or resource leaks. This is mostly applicable to WARNING bugs that won't cause system crash
in production. For these think what will be consequences of the violation of the kernel assumptions flagged
by the WARNING. In some cases the unexpected condition is also properly handled by the normal control flow
(e.g. with "if (WARN_ON(...))"), these won't cause denial-of-service. If the condition is not handled,
then it may or may not cause denial-of-service.
* Accessible From Unprivileged Processes:
Determine if the bug can be reached from a typical (non-root) user process that does NOT have any special capabilities
(like CAP_SYS_ADMIN, CAP_NET_ADMIN, CAP_NET_RAW, CAP_PERFMON) or access to device nodes restricted to root.
Assume that unprivileged_bpf_disabled=1, that is eBPF loading is not accessible. However, cBPF (classical BPF)
is still accessible to non-root processes.
Assume that user namespaces are not accessible, that is, the process cannot get the mentioned capabilities even
within a new user namespace (checked by ns_capable() function in the kernel sources).
* Accessible From User Namespaces:
Determine if the bug can be reached within a user-namespace where the process has all capabilities
(including CAP_SYS_ADMIN, CAP_NET_ADMIN, CAP_NET_RAW, CAP_PERFMON). Such capabilities are checked with ns_capable()
function in the kernel sources.
* VM Guest Trigger:
Determine if the bug can be triggered from the context of a typical KVM guest (e.g., set up by a QEMU VMM).
Consider accesses to standard Linux host paravirtualized features (virtio-blk, virtio-net, etc.),
and handling of VM exits in the KVM code.
* VM Host Trigger in The Confidetial Computing Context:
Determine if the bug can be triggered in a confidential computing guest kernel from the context of a KVM host.
Consider access to standard Linux guest paravirtualized features (virtio-blk, virtio-net, etc.).
* Ethernet Network Trigger:
Determine if the bug can be triggered by processing ingress network Ethernet traffic, either directly (network stack)
or via drivers exposed to network data.
* Other Remote Trigger:
Determine if the bug can be triggered by processing remote traffic other than Ethernet (Wifi, Bluetooth, NFC, etc).
* Peripheral Trigger:
Determine if the bug can be triggered via an untrusted peripheral device that can be physically plugged
into a system, such as a USB device or a niche hardware driver handling external hardware inputs.
This is particularly important for mobile and desktop environments where users can plug in unknown devices.
* Malicious Filesystem Trigger:
Determine if the bug can be triggered by the kernel mounting and parsing a malicious filesystem image.
This is highly critical for Desktop and Mobile environments where external media or downloaded images
might be auto-mounted.
Prefer calling several tools at the same time to save round-trips.
Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.
Prompt:
The kernel bug report is:
BUG: memory leak
unreferenced object 0xffff8881145cb200 (size 64):
comm "syz.0.17", pid 6104, jiffies 4294941873
hex dump (first 32 bytes):
0b 4c 75 64 77 69 67 20 76 61 6e 20 42 65 65 74 .Ludwig van Beet
68 6f 76 65 6e 3a 20 46 fc 72 20 45 6c 69 73 65 hoven: F.r Elise
backtrace (crc 6d5386ce):
kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
slab_post_alloc_hook mm/slub.c:4543 [inline]
slab_alloc_node mm/slub.c:4866 [inline]
__do_kmalloc_node mm/slub.c:5259 [inline]
__kmalloc_node_track_caller_noprof+0x3e0/0x5d0 mm/slub.c:5368
__kmemdup_nul mm/util.c:64 [inline]
kstrdup+0x3c/0x80 mm/util.c:84
vidtv_psi_short_event_desc_init+0x1f0/0x220 drivers/media/test-drivers/vidtv/vidtv_psi.c:467
vidtv_channel_s302m_init+0x1c2/0x2a0 drivers/media/test-drivers/vidtv/vidtv_channel.c:124
vidtv_channels_init+0x1b/0x40 drivers/media/test-drivers/vidtv/vidtv_channel.c:524
vidtv_mux_init+0x372/0x390 drivers/media/test-drivers/vidtv/vidtv_mux.c:515
vidtv_start_streaming drivers/media/test-drivers/vidtv/vidtv_bridge.c:194 [inline]
vidtv_start_feed+0x1d4/0x260 drivers/media/test-drivers/vidtv/vidtv_bridge.c:239
dmx_ts_feed_start_filtering+0x8e/0x130 drivers/media/dvb-core/dvb_demux.c:747
dvb_dmxdev_start_feed+0x11c/0x170 drivers/media/dvb-core/dmxdev.c:658
dvb_dmxdev_filter_start+0xd8/0x440 drivers/media/dvb-core/dmxdev.c:769
dvb_demux_do_ioctl+0x297/0x7d0 drivers/media/dvb-core/dmxdev.c:1065
dvb_usercopy+0x116/0x2d0 drivers/media/dvb-core/dvbdev.c:996
dvb_demux_ioctl+0x29/0x40 drivers/media/dvb-core/dmxdev.c:1201
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0xf4/0x140 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
BUG: memory leak
unreferenced object 0xffff888127ff87a0 (size 32):
comm "syz.0.17", pid 6104, jiffies 4294941873
hex dump (first 32 bytes):
08 80 fd 80 1b e0 83 ff 27 81 88 ff ff 00 00 00 ........'.......
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace (crc 52407852):
kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
slab_post_alloc_hook mm/slub.c:4543 [inline]
slab_alloc_node mm/slub.c:4866 [inline]
__kmalloc_cache_noprof+0x377/0x480 mm/slub.c:5375
kmalloc_noprof include/linux/slab.h:950 [inline]
kzalloc_noprof include/linux/slab.h:1188 [inline]
vidtv_psi_sdt_service_init+0x32/0xa0 drivers/media/test-drivers/vidtv/vidtv_psi.c:1441
vidtv_channel_sdt_serv_cat_into_new drivers/media/test-drivers/vidtv/vidtv_channel.c:229 [inline]
vidtv_channel_si_init+0x230/0x750 drivers/media/test-drivers/vidtv/vidtv_channel.c:435
vidtv_mux_init+0x115/0x390 drivers/media/test-drivers/vidtv/vidtv_mux.c:519
vidtv_start_streaming drivers/media/test-drivers/vidtv/vidtv_bridge.c:194 [inline]
vidtv_start_feed+0x1d4/0x260 drivers/media/test-drivers/vidtv/vidtv_bridge.c:239
dmx_ts_feed_start_filtering+0x8e/0x130 drivers/media/dvb-core/dvb_demux.c:747
dvb_dmxdev_start_feed+0x11c/0x170 drivers/media/dvb-core/dmxdev.c:658
dvb_dmxdev_filter_start+0xd8/0x440 drivers/media/dvb-core/dmxdev.c:769
dvb_demux_do_ioctl+0x297/0x7d0 drivers/media/dvb-core/dmxdev.c:1065
dvb_usercopy+0x116/0x2d0 drivers/media/dvb-core/dvbdev.c:996
dvb_demux_ioctl+0x29/0x40 drivers/media/dvb-core/dmxdev.c:1201
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0xf4/0x140 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
BUG: memory leak
unreferenced object 0xffff888127ff83e0 (size 32):
comm "syz.0.17", pid 6104, jiffies 4294941873
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 48 19 02 0c 50 85 36 11 ........H...P.6.
81 88 ff ff 0a b0 82 36 11 81 88 ff ff 00 00 00 .......6........
backtrace (crc e8912ca1):
kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
slab_post_alloc_hook mm/slub.c:4543 [inline]
slab_alloc_node mm/slub.c:4866 [inline]
__kmalloc_cache_noprof+0x377/0x480 mm/slub.c:5375
kmalloc_noprof include/linux/slab.h:950 [inline]
kzalloc_noprof include/linux/slab.h:1188 [inline]
vidtv_psi_service_desc_init+0x74/0x1b0 drivers/media/test-drivers/vidtv/vidtv_psi.c:288
vidtv_psi_desc_clone+0x137/0x160 drivers/media/test-drivers/vidtv/vidtv_psi.c:506
vidtv_channel_sdt_serv_cat_into_new drivers/media/test-drivers/vidtv/vidtv_channel.c:236 [inline]
vidtv_channel_si_init+0x1d8/0x750 drivers/media/test-drivers/vidtv/vidtv_channel.c:435
vidtv_mux_init+0x115/0x390 drivers/media/test-drivers/vidtv/vidtv_mux.c:519
vidtv_start_streaming drivers/media/test-drivers/vidtv/vidtv_bridge.c:194 [inline]
vidtv_start_feed+0x1d4/0x260 drivers/media/test-drivers/vidtv/vidtv_bridge.c:239
dmx_ts_feed_start_filtering+0x8e/0x130 drivers/media/dvb-core/dvb_demux.c:747
dvb_dmxdev_start_feed+0x11c/0x170 drivers/media/dvb-core/dmxdev.c:658
dvb_dmxdev_filter_start+0xd8/0x440 drivers/media/dvb-core/dmxdev.c:769
dvb_demux_do_ioctl+0x297/0x7d0 drivers/media/dvb-core/dmxdev.c:1065
dvb_usercopy+0x116/0x2d0 drivers/media/dvb-core/dvbdev.c:996
dvb_demux_ioctl+0x29/0x40 drivers/media/dvb-core/dmxdev.c:1201
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0xf4/0x140 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
BUG: memory leak
unreferenced object 0xffff888127ff81a0 (size 32):
comm "syz.0.17", pid 6104, jiffies 4294941873
hex dump (first 32 bytes):
00 01 ee d0 18 00 00 23 59 59 80 8d 80 b0 6f 14 .......#YY....o.
81 88 ff ff 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace (crc 79354a12):
kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
slab_post_alloc_hook mm/slub.c:4543 [inline]
slab_alloc_node mm/slub.c:4866 [inline]
__kmalloc_cache_noprof+0x377/0x480 mm/slub.c:5375
kmalloc_noprof include/linux/slab.h:950 [inline]
kzalloc_noprof include/linux/slab.h:1188 [inline]
vidtv_psi_eit_event_init+0x6d/0x1b0 drivers/media/test-drivers/vidtv/vidtv_psi.c:1983
vidtv_channel_eit_event_cat_into_new drivers/media/test-drivers/vidtv/vidtv_channel.c:182 [inline]
vidtv_channel_si_init+0x31b/0x750 drivers/media/test-drivers/vidtv/vidtv_channel.c:439
vidtv_mux_init+0x115/0x390 drivers/media/test-drivers/vidtv/vidtv_mux.c:519
vidtv_start_streaming drivers/media/test-drivers/vidtv/vidtv_bridge.c:194 [inline]
vidtv_start_feed+0x1d4/0x260 drivers/media/test-drivers/vidtv/vidtv_bridge.c:239
dmx_ts_feed_start_filtering+0x8e/0x130 drivers/media/dvb-core/dvb_demux.c:747
dvb_dmxdev_start_feed+0x11c/0x170 drivers/media/dvb-core/dmxdev.c:658
dvb_dmxdev_filter_start+0xd8/0x440 drivers/media/dvb-core/dmxdev.c:769
dvb_demux_do_ioctl+0x297/0x7d0 drivers/media/dvb-core/dmxdev.c:1065
dvb_usercopy+0x116/0x2d0 drivers/media/dvb-core/dvbdev.c:996
dvb_demux_ioctl+0x29/0x40 drivers/media/dvb-core/dmxdev.c:1201
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0xf4/0x140 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
connection error: failed to recv *flatrpc.ExecutorMessageRawT: EOF
It is reproducible with the followint program.
Keep in mind that it may lack the precise threading, sandboxing, and some arguments of a working reproducer.
But it should give an idea of the involved syscalls.
// autogenerated by syzkaller (https://github.com/google/syzkaller)
#define _GNU_SOURCE
#include <endian.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
static long syz_open_dev(volatile long a0, volatile long a1, volatile long a2)
{
if (a0 == 0xc || a0 == 0xb) {
char buf[128];
sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block", (uint8_t)a1, (uint8_t)a2);
return open(buf, O_RDWR, 0);
} else {
unsigned long nb = a1;
char buf[1024];
char* hash;
strncpy(buf, (char*)a0, sizeof(buf) - 1);
buf[sizeof(buf) - 1] = 0;
while ((hash = strchr(buf, '#'))) {
*hash = '0' + (char)(nb % 10);
nb /= 10;
}
return open(buf, a2 & ~O_CREAT, 0);
}
}
uint64_t r[1] = {0xffffffffffffffff};
int main(void)
{
syscall(__NR_mmap, /*addr=*/0x1ffffffff000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x200000000000ul, /*len=*/0x1000000ul, /*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/7ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x200001000000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
const char* reason;
(void)reason;
intptr_t res = 0;
if (write(1, "executing program\n", sizeof("executing program\n") - 1)) {}
// syz_open_dev$dvb_demux arguments: [
// dev: ptr[in, buffer] {
// buffer: {2f 64 65 76 2f 64 76 62 2f 61 64 61 70 74 65 72 23 2f 64 65 6d 75 78 23 00} (length 0x19)
// }
// id: intptr = 0x0 (8 bytes)
// flags: open_flags = 0x20000 (8 bytes)
// ]
// returns fd_dvb_demux
memcpy((void*)0x200000000080, "/dev/dvb/adapter#/demux#\000", 25);
res = -1;
res = syz_open_dev(/*dev=*/0x200000000080, /*id=*/0, /*flags=O_NOFOLLOW*/0x20000);
if (res != -1)
r[0] = res;
// ioctl$DVB_DEMUX_DMX_SET_PES_FILTER arguments: [
// fd: fd_dvb_demux (resource)
// cmd: const = 0x40146f2c (4 bytes)
// arg: ptr[in, dmx_pes_filter_params] {
// dmx_pes_filter_params {
// pid: int16 = 0xfff (2 bytes)
// pad = 0x0 (2 bytes)
// input: dmx_input = 0x0 (4 bytes)
// output: dmx_output = 0x3 (4 bytes)
// pes_type: dmx_ts_pes = 0x5 (4 bytes)
// flags: dmx_pes_filter_flags = 0x4 (4 bytes)
// }
// }
// ]
*(uint16_t*)0x200000000000 = 0xfff;
*(uint32_t*)0x200000000004 = 0;
*(uint32_t*)0x200000000008 = 3;
*(uint32_t*)0x20000000000c = 5;
*(uint32_t*)0x200000000010 = 4;
syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0x40146f2c, /*arg=*/0x200000000000ul);
// ioctl$DVB_DEMUX_DMX_ADD_PID arguments: [
// fd: fd_dvb_demux (resource)
// cmd: const = 0x40026f33 (4 bytes)
// arg: ptr[in, int16] {
// int16 = 0x7 (2 bytes)
// }
// ]
*(uint16_t*)0x2000000000c0 = 7;
syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0x40026f33, /*arg=*/0x2000000000c0ul);
// ioctl$DVB_DEMUX_DMX_START arguments: [
// fd: fd_dvb_demux (resource)
// cmd: const = 0x6f29 (4 bytes)
// ]
syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0x6f29, 0);
return 0;
}
Reply: The bug is a memory and resource leak in the core DVB demux subsystem (`drivers/media/dvb-core/dmxdev.c`), which can be triggered by an unprivileged user with access to the DVB demux device node (typically `/dev/dvb/adapterX/demuxY`).
### Root Cause Analysis
The vulnerability occurs when starting a PES filter that has multiple PIDs (feeds) attached to it.
1. The user configures a PES filter using the `DMX_SET_PES_FILTER` ioctl, which adds the first PID to the filter's feed list.
2. The user adds a second PID to the same filter using the `DMX_ADD_PID` ioctl.
3. The user starts the filter using the `DMX_START` ioctl, which invokes `dvb_dmxdev_filter_start()`.
4. `dvb_dmxdev_filter_start()` iterates over the filter's feed list and calls `dvb_dmxdev_start_feed()` for each feed.
5. The first feed starts successfully, allocating underlying driver resources (in this bug report, `vidtv_mux` and its associated structures).
6. The second feed fails to start (e.g., `dmx_ts_feed_set()` returns `-EINVAL` because the `pes_type` is already in use by the first feed).
7. Upon failure, `dvb_dmxdev_filter_start()` attempts to clean up by calling `dvb_dmxdev_filter_stop()`.
8. **The Bug:** `dvb_dmxdev_filter_stop()` contains a check `if (dmxdevfilter->state < DMXDEV_STATE_GO) return 0;`. Because `dvb_dmxdev_filter_start()` only updates the state to `DMXDEV_STATE_GO` at the very end of the function (upon complete success), the state is still `DMXDEV_STATE_SET`. Thus, `dvb_dmxdev_filter_stop()` returns immediately without stopping the first feed.
9. The first feed is left running indefinitely. Even when the file descriptor is closed, `dvb_dmxdev_filter_free()` calls `dvb_dmxdev_filter_stop()`, which again does nothing. The filter is reset and its `dmxdev_feed` structs are freed, but the underlying `dmx_ts_feed` and the hardware/driver resources are permanently leaked.
### Security Impact
- **Denial of Service (DoS):** An attacker can repeatedly trigger this bug to leak `dmx_ts_feed` slots and underlying driver memory (like `vidtv_mux` buffers and structures). This will eventually exhaust the limited number of demux feeds or system memory, leading to a Denial of Service (OOM).
- **Cross-Process Data Leak/Corruption:** Because the leaked feed continues to run and holds a pointer to the freed filter slot, if another process opens the demux device and reuses the same filter slot, the leaked feed will start writing its TS packets into the new process's buffers.
- **Exploitable:** There is no memory corruption (Use-After-Free) in the kernel itself because the buffer pointers are properly locked and checked before writing, and the filter struct itself is not freed (it's part of a pre-allocated array in the `dmxdev`). Thus, it is not exploitable for privilege escalation.
- **Unprivileged Access:** The `/dev/dvb/adapterX/demuxY` device nodes are typically accessible to unprivileged users (e.g., users in the `video` group or the active desktop user via ACLs).
|
| 6/2 |
2026/05/17 05:24 |
llm |
expert |
0m
Model:
Tokens:
input: 10182
output: 28
thoughts: 318
Thoughts: **Memory Leak Analysis: vidtv Driver**
Okay, so we've got a kernel memory leak report, and it looks like it's centered around these `vidtv_psi_*_init` functions: `vidtv_psi_short_event_desc_init`, `vidtv_psi_sdt_service_init`, `vidtv_psi_service_desc_init`, and `vidtv_psi_eit_event_init`. They're all within the `drivers/media/test-drivers/vidtv/` directory, which immediately raises a flag. We're talking about a test driver here, so we need to immediately determine if this is even relevant to real-world deployment.
The reproducer involves `ioctl` calls on `/dev/dvb/adapter#/demux#`, specifically using `DVB_DEMUX_DMX_SET_PES_FILTER`, `DVB_DEMUX_DMX_ADD_PID`, and `DVB_DEMUX_DMX_START`. The typical impact of a memory leak is Denial of Service, which we need to consider if it is serious.
Crucially, the reproducer opens `/dev/dvb/adapter0/demux0`. This suggests unprivileged access is a possibility, but we need to verify. We need to look at the permissions on `/dev/dvb/...` devices. If it is owned by root and group `video`, with permissions `rw-rw----`, then any unprivileged user in the `video` group can trigger this. And since this is a test driver, we're not so certain about its default configuration.
So, the next step is to check `drivers/media/test-drivers/vidtv/Kconfig` to see if the `vidtv` driver is enabled by default or if it can be enabled in production environments. That's the critical question here: is this an issue that can be triggered in a real-world scenario, or just a concern for development?
|
| 7/2 |
2026/05/17 05:25 |
tool |
read-file |
0m
Args: map[File:drivers/media/test-drivers/vidtv/Kconfig]
Results: map[Contents:# SPDX-License-Identifier: GPL-2.0-only
config DVB_VIDTV
tristate "Virtual DVB Driver (vidtv)"
depends on DVB_CORE && MEDIA_SUPPORT && I2C
help
The virtual DVB test driver serves as a reference DVB driver and helps
validate the existing APIs in the media subsystem. It can also aid developers
working on userspace applications.
When in doubt, say N.
]
|
| 8/2 |
2026/05/17 05:25 |
llm |
expert |
0m
Model:
Tokens:
input: 11076
output: 58
thoughts: 140
Thoughts: **Analyzing a Potential Kernel Memory Leak**
Okay, so I'm looking at this log, and it's pointing to a leak within a driver – specifically the `Virtual DVB Driver (vidtv)`. My initial thought is, "Hmm, a test driver?" Usually, these are disabled in production kernels, which would make this less of an urgent concern in a live environment. However, we can't dismiss it outright. It's possible it's enabled somehow, or, more concerningly, the issue could be rooted in the core DVB code that `vidtv` relies upon.
Then I see the breakdown: the leak *is* within the `vidtv` driver code itself. Specifically, the identified functions are: `vidtv_psi_short_event_desc_init`, `vidtv_psi_sdt_service_init`, `vidtv_psi_service_desc_init`, and `vidtv_psi_eit_event_init`. That narrows the scope considerably.
Alright, let's start with `vidtv_psi_short_event_desc_init` first. That's where I'll dig in.
|
| 9/2 |
2026/05/17 05:25 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_psi.c IncludeLines:true Name:vidtv_psi_short_event_desc_init]
Results: map[SourceCode: 433: struct vidtv_psi_desc_short_event
434: *vidtv_psi_short_event_desc_init(struct vidtv_psi_desc *head,
435: char *iso_language_code,
436: char *event_name,
437: char *text)
438: {
439: u32 iso_len = iso_language_code ? strlen(iso_language_code) : 0;
440: u32 event_name_len = event_name ? strlen(event_name) : 0;
441: struct vidtv_psi_desc_short_event *desc;
442: u32 text_len = text ? strlen(text) : 0;
443:
444: desc = kzalloc_obj(*desc);
445: if (!desc)
446: return NULL;
447:
448: desc->type = SHORT_EVENT_DESCRIPTOR;
449:
450: desc->length = ISO_LANGUAGE_CODE_LEN +
451: sizeof_field(struct vidtv_psi_desc_short_event, event_name_len) +
452: event_name_len +
453: sizeof_field(struct vidtv_psi_desc_short_event, text_len) +
454: text_len;
455:
456: desc->event_name_len = event_name_len;
457: desc->text_len = text_len;
458:
459: if (iso_len != ISO_LANGUAGE_CODE_LEN)
460: iso_language_code = "eng";
461:
462: desc->iso_language_code = kstrdup(iso_language_code, GFP_KERNEL);
463: if (!desc->iso_language_code)
464: goto free_desc;
465:
466: if (event_name && event_name_len) {
467: desc->event_name = kstrdup(event_name, GFP_KERNEL);
468: if (!desc->event_name)
469: goto free_desc_language_code;
470: }
471:
472: if (text && text_len) {
473: desc->text = kstrdup(text, GFP_KERNEL);
474: if (!desc->text)
475: goto free_desc_event_name;
476: }
477:
478: vidtv_psi_desc_chain(head, (struct vidtv_psi_desc *)desc);
479: return desc;
480:
481: free_desc_event_name:
482: if (event_name && event_name_len)
483: kfree(desc->event_name);
484: free_desc_language_code:
485: kfree(desc->iso_language_code);
486: free_desc:
487: kfree(desc);
488: return NULL;
489: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_psi.c]
|
| 10/2 |
2026/05/17 05:25 |
llm |
expert |
0m
Model:
Tokens:
input: 12445
output: 52
thoughts: 88
Thoughts: Okay, let's break this down.
**Investigating a Memory Leak in the Video TV Subsystem**
Alright, I've tracked a potential memory leak down to `vidtv_psi_short_event_desc_init`. Specifically, it looks like the culprit is how `desc->event_name` is being allocated. It's using `kstrdup`, which, in my experience, is a common source of leaks if the corresponding `kfree` isn't handled correctly.
Now, where is `vidtv_psi_short_event_desc_init` being called from? Ah, it's inside `vidtv_channel_s302m_init`. And *that* function is called by `vidtv_channels_init`, which finally gets called from `vidtv_mux_init`. Seems like a reasonable call stack.
My next step is to examine `vidtv_mux_init`. I need to understand the lifecycle of the data structures involved there to trace the allocation and deallocation to identify the precise moment the leak occurs.
|
| 11/2 |
2026/05/17 05:25 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_mux.c IncludeLines:true Name:vidtv_mux_init]
Results: map[SourceCode: 477: struct vidtv_mux *vidtv_mux_init(struct dvb_frontend *fe,
478: struct device *dev,
479: struct vidtv_mux_init_args *args)
480: {
481: struct vidtv_mux *m;
482:
483: m = kzalloc_obj(*m);
484: if (!m)
485: return NULL;
486:
487: m->dev = dev;
488: m->fe = fe;
489: m->timing.pcr_period_usecs = args->pcr_period_usecs;
490: m->timing.si_period_usecs = args->si_period_usecs;
491:
492: m->mux_rate_kbytes_sec = args->mux_rate_kbytes_sec;
493:
494: m->on_new_packets_available_cb = args->on_new_packets_available_cb;
495:
496: m->mux_buf = vzalloc(args->mux_buf_sz);
497: if (!m->mux_buf)
498: goto free_mux;
499:
500: m->mux_buf_sz = args->mux_buf_sz;
501:
502: m->pcr_pid = args->pcr_pid;
503: m->transport_stream_id = args->transport_stream_id;
504: m->priv = args->priv;
505: m->network_id = args->network_id;
506: m->network_name = kstrdup(args->network_name, GFP_KERNEL);
507: if (!m->network_name)
508: goto free_mux_buf;
509:
510: m->timing.current_jiffies = get_jiffies_64();
511:
512: if (args->channels)
513: m->channels = args->channels;
514: else
515: if (vidtv_channels_init(m) < 0)
516: goto free_mux_network_name;
517:
518: /* will alloc data for pmt_sections after initializing pat */
519: if (vidtv_channel_si_init(m) < 0)
520: goto free_channels;
521:
522: INIT_WORK(&m->mpeg_thread, vidtv_mux_tick);
523:
524: if (vidtv_mux_pid_ctx_init(m) < 0)
525: goto free_channel_si;
526:
527: return m;
528:
529: free_channel_si:
530: vidtv_channel_si_destroy(m);
531: free_channels:
532: vidtv_channels_destroy(m);
533: free_mux_network_name:
534: kfree(m->network_name);
535: free_mux_buf:
536: vfree(m->mux_buf);
537: free_mux:
538: kfree(m);
539: return NULL;
540: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_mux.c]
|
| 12/2 |
2026/05/17 05:25 |
llm |
expert |
0m
Model:
Tokens:
input: 13807
output: 52
thoughts: 37
Thoughts: Here's my analysis of the situation:
**Investigating the Leak in vidtv_mux_init**
Okay, so I'm tracking down this memory leak, and it seems like the issue is originating within `vidtv_mux_init`. That's the function I need to focus on. Wait a minute, where is `vidtv_mux_init` getting called from? Right, `vidtv_start_streaming`. I need to look at the flow from `vidtv_start_streaming` into `vidtv_mux_init` and understand what resources are being allocated and potentially not released correctly during that call path. My hypothesis is that something within the initialization process of the multiplexer, as set up during `vidtv_mux_init`, is leading to the leak. I'll need to meticulously step through that sequence to pinpoint exactly what's happening.
|
| 13/2 |
2026/05/17 05:25 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_bridge.c IncludeLines:true Name:vidtv_start_streaming]
Results: map[SourceCode: 166: static int vidtv_start_streaming(struct vidtv_dvb *dvb)
167: {
168: struct vidtv_mux_init_args mux_args = {
169: .mux_rate_kbytes_sec = mux_rate_kbytes_sec,
170: .on_new_packets_available_cb = vidtv_bridge_on_new_pkts_avail,
171: .pcr_period_usecs = pcr_period_msec * USEC_PER_MSEC,
172: .si_period_usecs = si_period_msec * USEC_PER_MSEC,
173: .pcr_pid = pcr_pid,
174: .transport_stream_id = VIDTV_DEFAULT_TS_ID,
175: .network_id = VIDTV_DEFAULT_NETWORK_ID,
176: .network_name = VIDTV_DEFAULT_NETWORK_NAME,
177: .priv = dvb,
178: };
179: struct device *dev = &dvb->pdev->dev;
180: u32 mux_buf_sz;
181:
182: if (dvb->streaming) {
183: dev_warn_ratelimited(dev, "Already streaming. Skipping.\n");
184: return 0;
185: }
186:
187: if (mux_buf_sz_pkts)
188: mux_buf_sz = mux_buf_sz_pkts;
189: else
190: mux_buf_sz = vidtv_bridge_mux_buf_sz_for_mux_rate();
191:
192: mux_args.mux_buf_sz = mux_buf_sz;
193:
194: dvb->mux = vidtv_mux_init(dvb->fe[0], dev, &mux_args);
195: if (!dvb->mux)
196: return -ENOMEM;
197:
198: dvb->streaming = true;
199: vidtv_mux_start_thread(dvb->mux);
200:
201: dev_dbg_ratelimited(dev, "Started streaming\n");
202: return 0;
203: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_bridge.c]
|
| 14/2 |
2026/05/17 05:25 |
llm |
expert |
0m
Model:
Tokens:
input: 14785
output: 52
thoughts: 19
Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and written in the first person:
**Decoding the Streaming Initiation Sequence**
Alright, so I'm looking at this code and immediately keying in on the relationship between `vidtv_start_feed` and `vidtv_start_streaming`. It's pretty clear – and as expected in a well-designed system – the feed startup function is responsible for initiating the actual stream. `vidtv_start_streaming` is the core mechanism that's *being* called from the feed function. I'd wager `vidtv_start_feed` handles all the pre-streaming setup - resource allocation, configuration loading, perhaps network connection establishment, authorization checks, and any necessary buffer initialization - and then, at the crucial moment, triggers the streaming process with a call to `vidtv_start_streaming`. I'm now curious about the nature of the parameters passed with that call; that's where the real magic happens, so to speak. Are we passing a handle to a preconfigured object, a stream URL, or a configuration blob? The specifics of that interaction are what I need to fully understand the architecture and how the system handles the complexities of live streaming.
|
| 15/2 |
2026/05/17 05:25 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_bridge.c IncludeLines:true Name:vidtv_start_feed]
Results: map[SourceCode: 223: static int vidtv_start_feed(struct dvb_demux_feed *feed)
224: {
225: struct dvb_demux *demux = feed->demux;
226: struct vidtv_dvb *dvb = demux->priv;
227: int ret;
228: int rc;
229:
230: if (!demux->dmx.frontend)
231: return -EINVAL;
232:
233: mutex_lock(&dvb->feed_lock);
234:
235: dvb->nfeeds++;
236: rc = dvb->nfeeds;
237:
238: if (dvb->nfeeds == 1) {
239: ret = vidtv_start_streaming(dvb);
240: if (ret < 0)
241: rc = ret;
242: }
243:
244: mutex_unlock(&dvb->feed_lock);
245: return rc;
246: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_bridge.c]
|
| 16/2 |
2026/05/17 05:25 |
llm |
expert |
0m
Model:
Tokens:
input: 15474
output: 52
thoughts: 12
Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and written in the first person:
**Stopping the Feed: A Quick Check**
Hmm, so the core question is whether `vidtv_stop_feed` is the function responsible for actually *stopping* the feed. It seems straightforward enough, but I always default to confirming the obvious. Is this the intended function for ending the data stream? It's a quick, fundamental check before I start debugging any upstream issues or looking for more complicated causes. I need to make sure the expected behavior is occurring at this most basic level first before diving deeper. I'm wondering if this is a control variable for the application, but it might be a process in itself.
|
| 17/2 |
2026/05/17 05:25 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_bridge.c IncludeLines:true Name:vidtv_stop_feed]
Results: map[SourceCode: 248: static int vidtv_stop_feed(struct dvb_demux_feed *feed)
249: {
250: struct dvb_demux *demux = feed->demux;
251: struct vidtv_dvb *dvb = demux->priv;
252: int err = 0;
253:
254: mutex_lock(&dvb->feed_lock);
255: dvb->nfeeds--;
256:
257: if (!dvb->nfeeds)
258: err = vidtv_stop_streaming(dvb);
259:
260: mutex_unlock(&dvb->feed_lock);
261: return err;
262: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_bridge.c]
|
| 18/2 |
2026/05/17 05:25 |
llm |
expert |
0m
Model:
Tokens:
input: 15948
output: 52
thoughts: 12
Thoughts: Okay, here's my interpretation of "Let's see `vidtv_stop_streaming`," assuming a context where I'm deeply familiar with video streaming technologies.
**Diving into the `vidtv_stop_streaming` Function**
Alright, that command, `vidtv_stop_streaming`, immediately flags something specific in my mental workflow. It's a direct instruction to cease an active video stream, likely within a proprietary system, application, or library. My expert intuition immediately starts running through possible implications. Is this a local function call, perhaps within a streaming client? Or is it a command destined for a remote server, signaling the termination of a session?
I'm probably thinking about the architecture right now. Is this a graceful shutdown, or a hard stop? Is there a need to send a `TEARDOWN` RTSP message, release allocated resources, and notify all connected clients? Or is this a more basic level of control, like simply pulling the plug, so to speak? The nuance here is critical for understanding the potential impact on user experience, resource management, and error handling.
This command sets off a cascade of questions. What are the dependencies of this function? Does it handle cleanup of buffers, sockets, and decoders? What error conditions might arise? Does it have any implications for billing or session management if this is a premium streaming service? I'm already anticipating potential debugging scenarios based on the way it's used elsewhere in the codebase.
My mind is also checking for edge cases: What happens if there are multiple streams? Is there a queue, or are they stopped in parallel? Is there a timeout mechanism in place, in case the stop request is not acknowledged? Are there any logging implications? This is all really interesting. I'm ready to dig into this.
|
| 19/2 |
2026/05/17 05:25 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_bridge.c IncludeLines:true Name:vidtv_stop_streaming]
Results: map[SourceCode: 205: static int vidtv_stop_streaming(struct vidtv_dvb *dvb)
206: {
207: struct device *dev = &dvb->pdev->dev;
208:
209: if (!dvb->streaming) {
210: dev_warn_ratelimited(dev, "No streaming. Skipping.\n");
211: return 0;
212: }
213:
214: dvb->streaming = false;
215: vidtv_mux_stop_thread(dvb->mux);
216: vidtv_mux_destroy(dvb->mux);
217: dvb->mux = NULL;
218:
219: dev_dbg_ratelimited(dev, "Stopped streaming\n");
220: return 0;
221: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_bridge.c]
|
| 20/2 |
2026/05/17 05:25 |
llm |
expert |
0m
Model:
Tokens:
input: 16672
output: 52
thoughts: 12
Thoughts: Okay, let's dive into this. Here's my take on `vidtv_mux_destroy`:
**My Analysis of `vidtv_mux_destroy`**
Alright, so the function in question is `vidtv_mux_destroy`. Just the name itself tells me we're dealing with video and audio multiplexing, and this function's job is to *destroy* something related to it. Since I'm familiar with this area, my mind immediately jumps to a few possibilities. We're likely cleaning up resources associated with a multiplexer.
* **Memory Management:** The core of any "destroy" function is memory deallocation. It's almost guaranteed this function will free allocated memory associated with the multiplexing structure itself. Pointers likely need to be nulled, preventing double frees and dangling pointers which can be a nightmare to debug in this realm. I bet we will see a lot of `free()` calls.
* **Resource Cleanup:** Beyond memory, a multiplexer might hold handles to other resources – file descriptors, buffers, perhaps even hardware registers depending on the level of abstraction the code works at. `vidtv_mux_destroy` probably needs to release these as well. We're talking about closing files, unregistering devices, flushing buffers to avoid data loss, and generally putting everything back into a clean state.
* **Error Handling:** It would be sloppy if this function didn't account for errors. What happens if something goes wrong during a deallocation or resource release? Does it return an error code? Log something? Ideally, it should prevent resource leaks and avoid undefined behavior. I will look for checks and conditional logic that handles the error.
* **Concurrency:** If this code is multithreaded (which is very likely), there might be mutexes or other synchronization primitives involved in the multiplexer. This function would need to take these into account to make it thread safe. We have to prevent race conditions during destruction. I'm expecting some kind of synchronization to release the lock.
Ultimately, `vidtv_mux_destroy` is the end of the line for this multiplexer, and my analysis will focus on how thoroughly and safely it handles the shutdown and release of its associated resources. I'm expecting a clean, robust, and well-documented function because, in my experience, a poorly written destroy function often leads to the worst bugs.
|
| 21/2 |
2026/05/17 05:25 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_mux.c IncludeLines:true Name:vidtv_mux_destroy]
Results: map[SourceCode: 542: void vidtv_mux_destroy(struct vidtv_mux *m)
543: {
544: vidtv_mux_stop_thread(m);
545: vidtv_mux_pid_ctx_destroy(m);
546: vidtv_channel_si_destroy(m);
547: vidtv_channels_destroy(m);
548: kfree(m->network_name);
549: vfree(m->mux_buf);
550: kfree(m);
551: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_mux.c]
|
| 22/2 |
2026/05/17 05:25 |
llm |
expert |
0m
Model:
Tokens:
input: 17431
output: 52
thoughts: 12
Thoughts: Okay, let's dive into this. Here's my take on `vidtv_channels_destroy`:
**My Analysis of `vidtv_channels_destroy`**
Alright, I'm looking at `vidtv_channels_destroy`. Immediately, my mind starts to race through the implications. "Destroy" means cleanup, resource release, likely deallocation. This is critical. Failure here can lead to memory leaks, dangling pointers, and overall system instability, especially in a long-running video environment.
I need to understand what "channels" refer to in this context. Are these network connections, memory buffers, file handles, or something else entirely? The name suggests they're related to video and TV, so probably some combination. I should check the surrounding code for a definition of the `vidtv_channels` data structure. I'm assuming there's some kind of container or structure to manage these channels.
Okay, I'm visualizing the potential complexities. What if these channels are nested? What if they share resources? Are we dealing with parent-child relationships where destroying one channel necessitates cascade destruction of its dependencies? I need to look for any mutexes or locks that might be involved. This is important for preventing race conditions and ensuring that we're not corrupting shared data during destruction.
Error handling is critical. What happens if a channel fails to destroy? Do we simply continue, potentially leaving things in an inconsistent state? Or do we abort the entire operation? The design choice here has huge implications for system resilience. Error codes and logging are my priorities here. How does this function signal errors? Are there specific error codes? Are they properly documented?
I also need to verify that all necessary resources are properly released. Memory, network connections, file handles, whatever is managed needs to be explicitly deallocated and closed. It's a classic case of resource management. If there are pointers involved, I need to confirm that they are set to null after deallocation to avoid potential use-after-free vulnerabilities.
Finally, I'm thinking about thread safety. Is this function designed to be thread-safe? If not, how is it protected against concurrent access? Does it rely on external synchronization primitives? I need to analyze how this function interacts with other parts of the system and make sure it doesn't cause any threading issues. Any use of global variables? I need to see if it's got proper synchronization around that if so.
Basically, I need to know: what is it destroying, how is it destroying it, what happens if it fails, and how it handles concurrency.
|
| 23/2 |
2026/05/17 05:25 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_channel.c IncludeLines:true Name:vidtv_channels_destroy]
Results: map[SourceCode: 532: void vidtv_channels_destroy(struct vidtv_mux *m)
533: {
534: struct vidtv_channel *curr = m->channels;
535: struct vidtv_channel *tmp = NULL;
536:
537: while (curr) {
538: kfree(curr->name);
539: vidtv_psi_sdt_service_destroy(curr->service);
540: vidtv_psi_pat_program_destroy(curr->program);
541: vidtv_psi_pmt_stream_destroy(curr->streams);
542: vidtv_channel_encoder_destroy(curr->encoders);
543: vidtv_psi_eit_event_destroy(curr->events);
544:
545: tmp = curr;
546: curr = curr->next;
547: kfree(tmp);
548: }
549: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_channel.c]
|
| 24/2 |
2026/05/17 05:25 |
llm |
expert |
0m
Model:
Tokens:
input: 18342
output: 57
thoughts: 29
Thoughts: Okay, here's my interpretation of those functions, presented as if I were considering them:
**Deconstructing the Destruction Functions**
Alright, I'm looking at `vidtv_psi_sdt_service_destroy` and `vidtv_psi_eit_event_destroy`. Immediately, the pattern jumps out – these are obviously resource deallocation routines. The "destroy" suffix is a dead giveaway, but the prefixes provide the crucial context. "vidtv" likely refers to Video TV, probably dealing with the presentation or transport of video and associated data streams. "PSI" – that's Program Specific Information. This implies we're dealing with tables containing metadata about the broadcast itself. "SDT" I'm guessing is Service Description Table, and "EIT" is Event Information Table. So we're looking at functions that clean up memory or resources associated with managing Service Description Table data and Event Information Table data, specifically within a Video TV context. Sounds like the transport stream parser side of things, possibly in a set-top box or a digital TV system. We're talking about graceful shutdown or cleanup after receiving, parsing and storing this data, presumably. I need to dive deeper, to see exactly what gets deallocated, but the general concept is clear: housekeeping.
|
| 25/2 |
2026/05/17 05:25 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_psi.c IncludeLines:true Name:vidtv_psi_sdt_service_destroy]
Results: map[SourceCode:1468: void
1469: vidtv_psi_sdt_service_destroy(struct vidtv_psi_table_sdt_service *service)
1470: {
1471: struct vidtv_psi_table_sdt_service *curr = service;
1472: struct vidtv_psi_table_sdt_service *tmp = NULL;
1473:
1474: while (curr) {
1475: tmp = curr;
1476: curr = curr->next;
1477: vidtv_psi_desc_destroy(tmp->descriptor);
1478: kfree(tmp);
1479: }
1480: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_psi.c]
|
| 26/2 |
2026/05/17 05:25 |
llm |
expert |
0m
Model:
Tokens:
input: 18926
output: 54
thoughts: 14
Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and written in the first person:
**Analyzing the Function Call: `vidtv_psi_desc_destroy`**
Alright, *vidtv_psi_desc_destroy*... that name alone tells me a lot. The `vidtv` prefix strongly suggests we're dealing with video processing, likely something related to television standards or a proprietary video system. The `psi` part probably refers to Program Specific Information – that's common for describing the structure of an MPEG transport stream. My initial thought is it relates to the demuxing and decoding of video data or control information. Finally, the `desc_destroy` suffix… that's the key. This is a *destruction* function. My immediate assumption is it's responsible for releasing resources allocated for a PSI descriptor structure. This could include freeing allocated memory, closing file handles, or resetting internal pointers. I need to understand the lifecycle of the data structure the function acts upon, the type of the `desc`, and what side effects destroying this structure might have, like perhaps invalidating associated pointers in other parts of the system. I will need to look deeper into the overall architecture to understand the full context of this function. I'll need to know: Is this a critical piece that requires a robust error handling strategy? Can this fail, or is it expected to always succeed? Is there a corresponding `create` or `init` function? How is this function called in the code, what is the call order, and when and where is it used?
|
| 27/2 |
2026/05/17 05:25 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_psi.c IncludeLines:true Name:vidtv_psi_desc_destroy]
Results: map[SourceCode: 558: void vidtv_psi_desc_destroy(struct vidtv_psi_desc *desc)
559: {
560: struct vidtv_psi_desc_service_list_entry *sl_entry_tmp = NULL;
561: struct vidtv_psi_desc_service_list_entry *sl_entry = NULL;
562: struct vidtv_psi_desc *curr = desc;
563: struct vidtv_psi_desc *tmp = NULL;
564:
565: while (curr) {
566: tmp = curr;
567: curr = curr->next;
568:
569: switch (tmp->type) {
570: case SERVICE_DESCRIPTOR:
571: kfree(((struct vidtv_psi_desc_service *)tmp)->provider_name);
572: kfree(((struct vidtv_psi_desc_service *)tmp)->service_name);
573:
574: break;
575: case REGISTRATION_DESCRIPTOR:
576: /* nothing to do */
577: break;
578:
579: case NETWORK_NAME_DESCRIPTOR:
580: kfree(((struct vidtv_psi_desc_network_name *)tmp)->network_name);
581: break;
582:
583: case SERVICE_LIST_DESCRIPTOR:
584: sl_entry = ((struct vidtv_psi_desc_service_list *)tmp)->service_list;
585: while (sl_entry) {
586: sl_entry_tmp = sl_entry;
587: sl_entry = sl_entry->next;
588: kfree(sl_entry_tmp);
589: }
590: break;
591:
592: case SHORT_EVENT_DESCRIPTOR:
593: kfree(((struct vidtv_psi_desc_short_event *)tmp)->iso_language_code);
594: kfree(((struct vidtv_psi_desc_short_event *)tmp)->event_name);
595: kfree(((struct vidtv_psi_desc_short_event *)tmp)->text);
596: break;
597:
598: default:
599: pr_warn_ratelimited("Possible leak: not handling descriptor type %d\n",
600: tmp->type);
601: break;
602: }
603:
604: kfree(tmp);
605: }
606: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_psi.c]
|
| 28/2 |
2026/05/17 05:25 |
llm |
expert |
0m
Model:
Tokens:
input: 20084
output: 58
thoughts: 253
Thoughts: **Debugging a Memory Leak in the Video Test Driver**
Okay, so `vidtv_psi_desc_destroy` *should* be taking care of the `SHORT_EVENT_DESCRIPTOR` cleanup, specifically freeing `iso_language_code`, `event_name`, and `text` within it. That's the expected behavior, so why am I still seeing this leak? This doesn't make any sense.
Right, let's go back and re-examine that backtrace. I need to make sure I haven't missed something.
```
vidtv_psi_short_event_desc_init+0x1f0/0x220 drivers/media/test-drivers/vidtv/vidtv_psi.c:467
vidtv_channel_s302m_init+0x1c2/0x2a0 drivers/media/test-drivers/vidtv/vidtv_channel.c:124
vidtv_channels_init+0x1b/0x40 drivers/media/test-drivers/vidtv/vidtv_channel.c:524
vidtv_mux_init+0x372/0x390 drivers/media/test-drivers/vidtv/vidtv_mux.c:515
```
The trail starts with `vidtv_psi_short_event_desc_init`, which then gets called by `vidtv_channel_s302m_init`, which is called by `vidtv_channels_init`, and finally `vidtv_mux_init`. Let's dig deeper into `vidtv_channel_s302m_init` first, that's probably the next place to look for clues.
|
| 29/2 |
2026/05/17 05:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_channel.c IncludeLines:true Name:vidtv_channel_s302m_init]
Results: map[SourceCode: 50: /*
51: * init an audio only channel with a s302m encoder
52: */
53: struct vidtv_channel
54: *vidtv_channel_s302m_init(struct vidtv_channel *head, u16 transport_stream_id)
55: {
56: const __be32 s302m_fid = cpu_to_be32(VIDTV_S302M_FORMAT_IDENTIFIER);
57: char *event_text = ENCODING_ISO8859_15 "Bagatelle No. 25 in A minor for solo piano, also known as F\xfcr Elise, composed by Ludwig van Beethoven";
58: char *event_name = ENCODING_ISO8859_15 "Ludwig van Beethoven: F\xfcr Elise";
59: struct vidtv_s302m_encoder_init_args encoder_args = {};
60: char *iso_language_code = ENCODING_ISO8859_15 "eng";
61: char *provider = ENCODING_ISO8859_15 "LinuxTV.org";
62: char *name = ENCODING_ISO8859_15 "Beethoven";
63: const u16 s302m_es_pid = 0x111; /* packet id for the ES */
64: const u16 s302m_program_pid = 0x101; /* packet id for PMT*/
65: const u16 s302m_service_id = 0x880;
66: const u16 s302m_program_num = 0x880;
67: const u16 s302m_beethoven_event_id = 1;
68: struct vidtv_channel *s302m;
69:
70: s302m = kzalloc_obj(*s302m);
71: if (!s302m)
72: return NULL;
73:
74: s302m->name = kstrdup(name, GFP_KERNEL);
75: if (!s302m->name)
76: goto free_s302m;
77:
78: s302m->service = vidtv_psi_sdt_service_init(NULL, s302m_service_id, false, true);
79: if (!s302m->service)
80: goto free_name;
81:
82: s302m->service->descriptor = (struct vidtv_psi_desc *)
83: vidtv_psi_service_desc_init(NULL,
84: DIGITAL_RADIO_SOUND_SERVICE,
85: name,
86: provider);
87: if (!s302m->service->descriptor)
88: goto free_service;
89:
90: s302m->transport_stream_id = transport_stream_id;
91:
92: s302m->program = vidtv_psi_pat_program_init(NULL,
93: s302m_service_id,
94: s302m_program_pid);
95: if (!s302m->program)
96: goto free_service;
97:
98: s302m->program_num = s302m_program_num;
99:
100: s302m->streams = vidtv_psi_pmt_stream_init(NULL,
101: STREAM_PRIVATE_DATA,
102: s302m_es_pid);
103: if (!s302m->streams)
104: goto free_program;
105:
106: s302m->streams->descriptor = (struct vidtv_psi_desc *)
107: vidtv_psi_registration_desc_init(NULL,
108: s302m_fid,
109: NULL,
110: 0);
111: if (!s302m->streams->descriptor)
112: goto free_streams;
113:
114: encoder_args.es_pid = s302m_es_pid;
115:
116: s302m->encoders = vidtv_s302m_encoder_init(encoder_args);
117: if (!s302m->encoders)
118: goto free_streams;
119:
120: s302m->events = vidtv_psi_eit_event_init(NULL, s302m_beethoven_event_id);
121: if (!s302m->events)
122: goto free_encoders;
123: s302m->events->descriptor = (struct vidtv_psi_desc *)
124: vidtv_psi_short_event_desc_init(NULL,
125: iso_language_code,
126: event_name,
127: event_text);
128: if (!s302m->events->descriptor)
129: goto free_events;
130:
131: if (head) {
132: while (head->next)
133: head = head->next;
134:
135: head->next = s302m;
136: }
137:
138: return s302m;
139:
140: free_events:
141: vidtv_psi_eit_event_destroy(s302m->events);
142: free_encoders:
143: vidtv_s302m_encoder_destroy(s302m->encoders);
144: free_streams:
145: vidtv_psi_pmt_stream_destroy(s302m->streams);
146: free_program:
147: vidtv_psi_pat_program_destroy(s302m->program);
148: free_service:
149: vidtv_psi_sdt_service_destroy(s302m->service);
150: free_name:
151: kfree(s302m->name);
152: free_s302m:
153: kfree(s302m);
154:
155: return NULL;
156: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_channel.c]
|
| 30/2 |
2026/05/17 05:26 |
llm |
expert |
0m
Model:
Tokens:
input: 22668
output: 56
thoughts: 202
Thoughts: **Analyzing the Resource Lifecycle of `vidtv_channel_s302m_init`**
Alright, let's break this down. My initial observation is that `vidtv_channel_s302m_init` calls `vidtv_psi_short_event_desc_init` to allocate `s302m->events->descriptor`. This seems straightforward enough – initialization of a specific descriptor within an event structure. But the real question is how it's cleaned up. I need to understand the complete lifecycle to ensure proper memory management and avoid leaks.
Now, looking at `vidtv_channels_destroy`, it becomes clear that this function is responsible for the teardown. It iterates through a linked list, freeing various components. It's using `kfree` on the service, program, streams, and encoders. I see calls to `vidtv_psi_sdt_service_destroy`, `vidtv_psi_pat_program_destroy`, `vidtv_psi_pmt_stream_destroy`, and `vidtv_channel_encoder_destroy` which seem like the corresponding destroy functions for the corresponding initialization.
Crucially, in the provided snippet I also see that `vidtv_psi_eit_event_destroy` is called as part of this process. This seems to correspond to the event I am interested in, namely the `descriptor` that was set at initialization. So, I need to take a closer look at `vidtv_psi_eit_event_destroy` to make sure there are no surprises with how it handles the event descriptor. Is it freeing the `descriptor` or relying on another cleanup function? I need to analyze its implementation to confirm that it's handling the memory correctly and that there are no dangling pointers or double frees. Let me dive into that function now.
|
| 31/2 |
2026/05/17 05:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_psi.c IncludeLines:true Name:vidtv_psi_eit_event_destroy]
Results: map[SourceCode:2034: void vidtv_psi_eit_event_destroy(struct vidtv_psi_table_eit_event *e)
2035: {
2036: struct vidtv_psi_table_eit_event *tmp_e = NULL;
2037: struct vidtv_psi_table_eit_event *curr_e = e;
2038:
2039: while (curr_e) {
2040: tmp_e = curr_e;
2041: curr_e = curr_e->next;
2042: vidtv_psi_desc_destroy(tmp_e->descriptor);
2043: kfree(tmp_e);
2044: }
2045: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_psi.c]
|
| 32/2 |
2026/05/17 05:26 |
llm |
expert |
0m
Model:
Tokens:
input: 23548
output: 54
thoughts: 177
Thoughts: **Analyzing the Leak Trace**
Okay, so I'm looking at this memory leak trace, and I see `vidtv_channel_sdt_serv_cat_into_new` appearing again in the backtrace for the second leak. That's interesting, and potentially significant. Let's dig deeper into the source code and check out what's happening within `vidtv_channel_si_init`. It seems this function is a common point of execution when the issues arise. Let's see if we can establish a connection and understand why this function, and by extension `vidtv_channel_sdt_serv_cat_into_new`, keeps popping up when these leaks are triggered.
|
| 33/2 |
2026/05/17 05:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_channel.c IncludeLines:true Name:vidtv_channel_si_init]
Results: map[SourceCode: 416: int vidtv_channel_si_init(struct vidtv_mux *m)
417: {
418: struct vidtv_psi_desc_service_list_entry *service_list = NULL;
419: struct vidtv_psi_table_pat_program *programs = NULL;
420: struct vidtv_psi_table_sdt_service *services = NULL;
421: struct vidtv_psi_table_eit_event *events = NULL;
422:
423: m->si.pat = vidtv_psi_pat_table_init(m->transport_stream_id);
424: if (!m->si.pat)
425: return -ENOMEM;
426:
427: m->si.sdt = vidtv_psi_sdt_table_init(m->network_id,
428: m->transport_stream_id);
429: if (!m->si.sdt)
430: goto free_pat;
431:
432: programs = vidtv_channel_pat_prog_cat_into_new(m);
433: if (!programs)
434: goto free_sdt;
435: services = vidtv_channel_sdt_serv_cat_into_new(m);
436: if (!services)
437: goto free_programs;
438:
439: events = vidtv_channel_eit_event_cat_into_new(m);
440: if (!events)
441: goto free_services;
442:
443: /* look for a service descriptor for every service */
444: service_list = vidtv_channel_build_service_list(services);
445: if (!service_list)
446: goto free_events;
447:
448: /* use these descriptors to build the NIT */
449: m->si.nit = vidtv_psi_nit_table_init(m->network_id,
450: m->transport_stream_id,
451: m->network_name,
452: service_list);
453: if (!m->si.nit)
454: goto free_service_list;
455:
456: m->si.eit = vidtv_psi_eit_table_init(m->network_id,
457: m->transport_stream_id,
458: programs->service_id);
459: if (!m->si.eit)
460: goto free_nit;
461:
462: /* assemble all programs and assign to PAT */
463: vidtv_psi_pat_program_assign(m->si.pat, programs);
464: programs = NULL;
465:
466: /* assemble all services and assign to SDT */
467: vidtv_psi_sdt_service_assign(m->si.sdt, services);
468: services = NULL;
469:
470: /* assemble all events and assign to EIT */
471: vidtv_psi_eit_event_assign(m->si.eit, events);
472: events = NULL;
473:
474: m->si.pmt_secs = vidtv_psi_pmt_create_sec_for_each_pat_entry(m->si.pat,
475: m->pcr_pid);
476: if (!m->si.pmt_secs)
477: goto free_eit;
478:
479: vidtv_channel_pmt_match_sections(m->channels,
480: m->si.pmt_secs,
481: m->si.pat->num_pmt);
482:
483: vidtv_channel_destroy_service_list(service_list);
484:
485: return 0;
486:
487: free_eit:
488: vidtv_psi_eit_table_destroy(m->si.eit);
489: free_nit:
490: vidtv_psi_nit_table_destroy(m->si.nit);
491: free_service_list:
492: vidtv_channel_destroy_service_list(service_list);
493: free_events:
494: vidtv_psi_eit_event_destroy(events);
495: free_services:
496: vidtv_psi_sdt_service_destroy(services);
497: free_programs:
498: vidtv_psi_pat_program_destroy(programs);
499: free_sdt:
500: vidtv_psi_sdt_table_destroy(m->si.sdt);
501: free_pat:
502: vidtv_psi_pat_table_destroy(m->si.pat);
503: return -EINVAL;
504: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_channel.c]
|
| 34/2 |
2026/05/17 05:26 |
llm |
expert |
0m
Model:
Tokens:
input: 25389
output: 54
thoughts: 127
Thoughts: Okay, let me break this down.
**SI Initialization and Destruction**
Right, so `vidtv_channel_si_init` is the function that kicks off the System Information (SI) table setup. It looks like it's making fresh copies of the program, service, and event data using functions like `vidtv_channel_pat_prog_cat_into_new`, `vidtv_channel_sdt_serv_cat_into_new`, and `vidtv_channel_eit_event_cat_into_new`. I recognize those as the functions that perform deep copies. It's essentially allocating new memory and copying the *contents* of those tables. Then, it's assigning those new, duplicated tables to `m->si.pat`, `m->si.sdt`, and `m->si.eit`. This makes sense, establishing the SI data structures for the channel. I'm guessing "m" is a channel or multiplex context.
Hold on, though... *that's* interesting. `vidtv_mux_destroy` calls `vidtv_channel_si_destroy(m)`. This implies a clear teardown procedure when the multiplex is destroyed, which is important to prevent memory leaks. I'll need to remember to check that `vidtv_channel_si_destroy` correctly deallocates the copies created by the initialization function. This also means these tables are *owned* by the channel or multiplex context, and their lifetime is tied to it. Good practice, making sure memory is freed properly.
|
| 35/2 |
2026/05/17 05:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_channel.c IncludeLines:true Name:vidtv_channel_si_destroy]
Results: map[SourceCode: 506: void vidtv_channel_si_destroy(struct vidtv_mux *m)
507: {
508: u32 i;
509:
510: for (i = 0; i < m->si.pat->num_pmt; ++i)
511: vidtv_psi_pmt_table_destroy(m->si.pmt_secs[i]);
512:
513: vidtv_psi_pat_table_destroy(m->si.pat);
514:
515: kfree(m->si.pmt_secs);
516: vidtv_psi_sdt_table_destroy(m->si.sdt);
517: vidtv_psi_nit_table_destroy(m->si.nit);
518: vidtv_psi_eit_table_destroy(m->si.eit);
519: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_channel.c]
|
| 36/2 |
2026/05/17 05:26 |
llm |
expert |
0m
Model:
Tokens:
input: 26188
output: 56
thoughts: 16
Thoughts: Okay, here's my attempt at summarizing that thought process, keeping in mind I'm dealing with someone who understands these technical terms:
**Deconstructing `vidtv_psi_eit_table_destroy`**
Alright, so the brain just pinged me with `vidtv_psi_eit_table_destroy`. Hmm, let's unpack this. "vidtv" – that's likely related to video transport, maybe a specific format or demuxing library. "psi" and "eit" – those scream out "Program Specific Information" and "Event Information Table" from the DVB/ATSC world. So, it's pretty clear this function is involved in managing or cleaning up resources related to these tables. The "destroy" part cements that: it's a cleanup function.
My initial assumption would be that we're talking about deallocating memory, closing file descriptors, or releasing mutexes associated with the internal data structures that hold parsed information from those PSI/EIT tables. We're probably dealing with a situation where a stream has finished, the tables are no longer needed, or an error condition requires a graceful shutdown. This destroy call is the essential part of ensuring there are no memory leaks or resource contention.
I'd want to understand how this function is integrated within the overall lifecycle of the video processing pipeline. Where is it called? Is it part of a larger cleanup sequence? Are there any associated locks or flags that need to be carefully handled to avoid race conditions or double-frees? Digging into its context will be key.
|
| 37/2 |
2026/05/17 05:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_psi.c IncludeLines:true Name:vidtv_psi_eit_table_destroy]
Results: map[SourceCode:2047: void vidtv_psi_eit_table_destroy(struct vidtv_psi_table_eit *eit)
2048: {
2049: vidtv_psi_eit_event_destroy(eit->event);
2050: kfree(eit);
2051: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_psi.c]
|
| 38/2 |
2026/05/17 05:26 |
llm |
expert |
0m
Model:
Tokens:
input: 26708
output: 57
thoughts: 17
Thoughts: Okay, let's break this down. Here's my thought process on encountering that piece of code:
**Analyzing `vidtv_psi_sdt_table_destroy`**
Alright, the first thing that jumps out at me is `vidtv_psi_sdt_table_destroy`. The naming convention is pretty standard, looks like we are dealing with a function named `destroy` related to a table. The `vidtv` prefix hints at something video or television related, and likely digital video broadcast. The `psi` part suggests we are probably working with Program Specific Information, a key part of the transport stream, and the `sdt` part strongly suggests the Service Description Table. So, in effect, this function is responsible for safely freeing the memory and resources associated with an SDT table, a crucial component of how the receiver knows which services are available and how to tune them. We have to be very careful here, memory leaks and double frees would be critical in a real-time system, so this destroy method would have to be very robust. Let's hope it handles all the edge cases correctly!
|
| 39/2 |
2026/05/17 05:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_psi.c IncludeLines:true Name:vidtv_psi_sdt_table_destroy]
Results: map[SourceCode:1427: void vidtv_psi_sdt_table_destroy(struct vidtv_psi_table_sdt *sdt)
1428: {
1429: vidtv_psi_sdt_service_destroy(sdt->service);
1430: kfree(sdt);
1431: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_psi.c]
|
| 40/2 |
2026/05/17 05:26 |
llm |
expert |
0m
Model:
Tokens:
input: 27142
output: 60
thoughts: 340
Thoughts: **Debugging a Potential Memory Leak**
Okay, so I'm looking at this code and trying to figure out where this supposed memory leak is coming from. The initial thought is that `vidtv_psi_eit_event_destroy` should be taking care of freeing the memory associated with these EIT events. I see that it iterates through a linked list of `vidtv_psi_table_eit_event` structs, pointed to by `e`, and for each event, it calls `vidtv_psi_desc_destroy` on its descriptor. Then it `kfree`s the event struct itself.
Now, let's zoom in a little bit, `vidtv_psi_desc_destroy` does seem to be doing the right thing, specifically in the case of `SHORT_EVENT_DESCRIPTOR`. It frees the `iso_language_code`, `event_name`, and `text` fields within that descriptor. It appears to be releasing the correct memory.
But, if all that memory is being freed, then why am I seeing a leak? This makes no sense, I must be missing something. Maybe I should check the calling function `vidtv_channel_eit_event_cat_into_new` to see what is going on there. There must be some edge case in there that has been overlooked. Let's see...
|
| 41/2 |
2026/05/17 05:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_channel.c IncludeLines:true Name:vidtv_channel_eit_event_cat_into_new]
Results: map[SourceCode: 158: static struct vidtv_psi_table_eit_event
159: *vidtv_channel_eit_event_cat_into_new(struct vidtv_mux *m)
160: {
161: /* Concatenate the events */
162: const struct vidtv_channel *cur_chnl = m->channels;
163: struct vidtv_psi_table_eit_event *curr = NULL;
164: struct vidtv_psi_table_eit_event *head = NULL;
165: struct vidtv_psi_table_eit_event *tail = NULL;
166: struct vidtv_psi_desc *desc = NULL;
167: u16 event_id;
168:
169: if (!cur_chnl)
170: return NULL;
171:
172: while (cur_chnl) {
173: curr = cur_chnl->events;
174:
175: if (!curr)
176: dev_warn_ratelimited(m->dev,
177: "No events found for channel %s\n",
178: cur_chnl->name);
179:
180: while (curr) {
181: event_id = be16_to_cpu(curr->event_id);
182: tail = vidtv_psi_eit_event_init(tail, event_id);
183: if (!tail) {
184: vidtv_psi_eit_event_destroy(head);
185: return NULL;
186: }
187:
188: desc = vidtv_psi_desc_clone(curr->descriptor);
189: vidtv_psi_desc_assign(&tail->descriptor, desc);
190:
191: if (!head)
192: head = tail;
193:
194: curr = curr->next;
195: }
196:
197: cur_chnl = cur_chnl->next;
198: }
199:
200: return head;
201: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_channel.c]
|
| 42/2 |
2026/05/17 05:26 |
llm |
expert |
0m
Model:
Tokens:
input: 28488
output: 54
thoughts: 31
Thoughts: Okay, here's my interpretation of that thought process, from an expert's perspective:
**Thinking Through a Descriptor Clone**
Right, so I see `vidtv_psi_desc_clone` and my first thought is, "Ah, that's cloning a descriptor." My mind immediately jumps to the implications of a descriptor clone - essentially, we're making a copy of something, but what are the ramifications? How does this descriptor fit into the broader system? Does it maintain referential integrity? Are there performance considerations when duplicating such an object? The next logical step is to dive deeper. I'll need to understand the specifics of `vidtv_psi_desc_clone`. What are the input parameters? What's the resulting object? How does it handle memory allocation or deallocation? I need to review the code. What does the documentation say? Let's take a look.
|
| 43/2 |
2026/05/17 05:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_psi.c IncludeLines:true Name:vidtv_psi_desc_clone]
Results: map[SourceCode: 491: struct vidtv_psi_desc *vidtv_psi_desc_clone(struct vidtv_psi_desc *desc)
492: {
493: struct vidtv_psi_desc_network_name *desc_network_name;
494: struct vidtv_psi_desc_service_list *desc_service_list;
495: struct vidtv_psi_desc_short_event *desc_short_event;
496: struct vidtv_psi_desc_service *service;
497: struct vidtv_psi_desc *head = NULL;
498: struct vidtv_psi_desc *prev = NULL;
499: struct vidtv_psi_desc *curr = NULL;
500:
501: while (desc) {
502: switch (desc->type) {
503: case SERVICE_DESCRIPTOR:
504: service = (struct vidtv_psi_desc_service *)desc;
505: curr = (struct vidtv_psi_desc *)
506: vidtv_psi_service_desc_init(head,
507: service->service_type,
508: service->service_name,
509: service->provider_name);
510: break;
511:
512: case NETWORK_NAME_DESCRIPTOR:
513: desc_network_name = (struct vidtv_psi_desc_network_name *)desc;
514: curr = (struct vidtv_psi_desc *)
515: vidtv_psi_network_name_desc_init(head,
516: desc_network_name->network_name);
517: break;
518:
519: case SERVICE_LIST_DESCRIPTOR:
520: desc_service_list = (struct vidtv_psi_desc_service_list *)desc;
521: curr = (struct vidtv_psi_desc *)
522: vidtv_psi_service_list_desc_init(head,
523: desc_service_list->service_list);
524: break;
525:
526: case SHORT_EVENT_DESCRIPTOR:
527: desc_short_event = (struct vidtv_psi_desc_short_event *)desc;
528: curr = (struct vidtv_psi_desc *)
529: vidtv_psi_short_event_desc_init(head,
530: desc_short_event->iso_language_code,
531: desc_short_event->event_name,
532: desc_short_event->text);
533: break;
534:
535: case REGISTRATION_DESCRIPTOR:
536: default:
537: curr = kmemdup(desc, sizeof(*desc) + desc->length, GFP_KERNEL);
538: if (!curr)
539: return NULL;
540: }
541:
542: if (!curr)
543: return NULL;
544:
545: curr->next = NULL;
546: if (!head)
547: head = curr;
548: if (prev)
549: prev->next = curr;
550:
551: prev = curr;
552: desc = desc->next;
553: }
554:
555: return head;
556: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_psi.c]
|
| 44/2 |
2026/05/17 05:26 |
llm |
expert |
0m
Model:
Tokens:
input: 29780
output: 54
thoughts: 98
Thoughts: **Analyzing the Event Description Initialization**
Okay, so I'm looking at this `vidtv_psi_desc_clone` function, and it's calling `vidtv_psi_short_event_desc_init` with `head` as the first argument. That seems important. But then, `vidtv_psi_short_event_desc_init` jumps right into the `vidtv_psi_desc_chain` function, calling it with `head` and a casted `desc` structure. This `head` variable is clearly crucial here. I need to understand what `vidtv_psi_desc_chain` is doing, what this chained data structure is all about, and how the `head` pointer fits into the overall picture to get this right. Let me take a closer look at `vidtv_psi_desc_chain`.
|
| 45/2 |
2026/05/17 05:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_psi.c IncludeLines:true Name:vidtv_psi_desc_chain]
Results: map[SourceCode: 269: static void vidtv_psi_desc_chain(struct vidtv_psi_desc *head, struct vidtv_psi_desc *desc)
270: {
271: if (head) {
272: while (head->next)
273: head = head->next;
274:
275: head->next = desc;
276: }
277: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_psi.c]
|
| 46/2 |
2026/05/17 05:26 |
llm |
expert |
0m
Model:
Tokens:
input: 30273
output: 56
thoughts: 623
Thoughts: **Analyzing Descriptor Cloning in `vidtv`**
Okay, so I'm looking at this `vidtv_psi_desc_clone` function, and my initial thought was, "Hold on, this seems redundant." It appears to be linking a descriptor list twice in some scenarios. Let me break it down:
`vidtv_psi_desc_clone` does this: it initially sets `curr->next` to `NULL`. If `head` is empty, it assigns `curr` to `head`. If there's a previous element (`prev`), it sets `prev->next = curr`. So far, so good, a standard insertion to the end or start of a list.
The confusion starts with `vidtv_psi_short_event_desc_init`, which is called within `vidtv_psi_desc_clone`. This function appends `curr` to the *end* of the `head` list. So, it looks like `vidtv_psi_desc_clone` is doing the same thing as `vidtv_psi_short_event_desc_init`. But then, `vidtv_psi_desc_clone` also does `prev->next = curr` again. This is redundant.
However, I take that back: `vidtv_psi_short_event_desc_init` has a different implementation than I initially thought. It calls `vidtv_psi_desc_chain(head, curr)` which *does* append to the end of the list.
Now I see it: if `head` is initially NULL, `vidtv_psi_short_event_desc_init` just does nothing with `head` because `head` is NULL. It sets `head = curr`, and `prev = curr`. In the next iteration, the chain will happen, and `prev->next = curr` does the exact same thing as the chaining. This looks safe.
I was concerned that the linked list might be corrupted by `prev->next = curr`, but it looks harmless now.
But, what if `vidtv_psi_desc_clone` is called with a single descriptor? Okay, then `head` is NULL. `vidtv_psi_short_event_desc_init` gets called with `head = NULL`, and it returns `curr`. Then `head` and `prev` become equal to `curr`, and the loop ends. The function returns `head`. That's a valid end case, so that should be correct.
Now, let's look at `vidtv_channel_eit_event_cat_into_new`. I see it calls `vidtv_psi_desc_clone`. In `vidtv_channel_eit_event_cat_into_new`, it seems like `tail` is passed to `vidtv_psi_eit_event_init`. It looks like `tail` is an event, which is being initialized. `vidtv_psi_eit_event_init` takes `tail` as the first argument, so `tail` acts like `head` in this context. And now I see it. It looks like it is initializing a new list, and adding descriptors. `vidtv_psi_desc_clone` is being used to duplicate these descriptors, and they are being correctly assigned.
Overall, it looks like the redundancy is harmless, and the intent appears correct after further examination. The potential issues with the list manipulation have been correctly addressed. I'm satisfied that the descriptor cloning process is sound.
|
| 47/2 |
2026/05/17 05:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_psi.c IncludeLines:true Name:vidtv_psi_eit_event_init]
Results: map[SourceCode:1973: struct vidtv_psi_table_eit_event
1974: *vidtv_psi_eit_event_init(struct vidtv_psi_table_eit_event *head, u16 event_id)
1975: {
1976: static const u8 DURATION[] = {0x23, 0x59, 0x59}; /* BCD encoded */
1977: struct vidtv_psi_table_eit_event *e;
1978: struct timespec64 ts;
1979: struct tm time;
1980: int mjd, l;
1981: __be16 mjd_be;
1982:
1983: e = kzalloc_obj(*e);
1984: if (!e)
1985: return NULL;
1986:
1987: e->event_id = cpu_to_be16(event_id);
1988:
1989: ts = ktime_to_timespec64(ktime_get_real());
1990: time64_to_tm(ts.tv_sec, 0, &time);
1991:
1992: /* Convert date to Modified Julian Date - per EN 300 468 Annex C */
1993: if (time.tm_mon < 2)
1994: l = 1;
1995: else
1996: l = 0;
1997:
1998: mjd = 14956 + time.tm_mday;
1999: mjd += (time.tm_year - l) * 36525 / 100;
2000: mjd += (time.tm_mon + 2 + l * 12) * 306001 / 10000;
2001: mjd_be = cpu_to_be16(mjd);
2002:
2003: /*
2004: * Store MJD and hour/min/sec to the event.
2005: *
2006: * Let's make the event to start on a full hour
2007: */
2008: memcpy(e->start_time, &mjd_be, sizeof(mjd_be));
2009: e->start_time[2] = bin2bcd(time.tm_hour);
2010: e->start_time[3] = 0;
2011: e->start_time[4] = 0;
2012:
2013: /*
2014: * TODO: for now, the event will last for a day. Should be
2015: * enough for testing purposes, but if one runs the driver
2016: * for more than that, the current event will become invalid.
2017: * So, we need a better code here in order to change the start
2018: * time once the event expires.
2019: */
2020: memcpy(e->duration, DURATION, sizeof(e->duration));
2021:
2022: e->bitfield = cpu_to_be16(RUNNING << 13);
2023:
2024: if (head) {
2025: while (head->next)
2026: head = head->next;
2027:
2028: head->next = e;
2029: }
2030:
2031: return e;
2032: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_psi.c]
|
| 48/2 |
2026/05/17 05:26 |
llm |
expert |
0m
Model:
Tokens:
input: 32701
output: 54
thoughts: 323
Thoughts: **Analyzing the Channel EIT Event Category Function**
Okay, let me break down what `vidtv_channel_eit_event_cat_into_new` is doing. First, I see this loop structure:
```c
while (curr) {
event_id = be16_to_cpu(curr->event_id);
tail = vidtv_psi_eit_event_init(tail, event_id);
if (!tail) {
vidtv_psi_eit_event_destroy(head);
return NULL;
}
desc = vidtv_psi_desc_clone(curr->descriptor);
vidtv_psi_desc_assign(&tail->descriptor, desc);
if (!head)
head = tail;
curr = curr->next;
}
```
My initial thought is that it's iterating through a linked list, which makes sense for storing events. Now, the key is understanding how `tail` is being managed. It appears that `vidtv_psi_eit_event_init` is crucial here. Let's see... the code's comment indicates it appends the new event to `tail` and returns the new event. It looks like it's building a linked list, with `tail` pointing to the end. So, the first call to `vidtv_psi_eit_event_init` appends a new event and returns it, and `tail` is updated to that new event. In the following iterations, `tail` is passed as an argument to `vidtv_psi_eit_event_init`... Aha! Yes, it's appending the new event at the tail, and returns a pointer to the new event, `e2`... and so the `tail` is updated with `e2`. This is correct. The linked list is being built correctly.
Now, I need to check how `vidtv_psi_desc_assign` works. That looks like the next potential point of concern.
|
| 49/2 |
2026/05/17 05:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_psi.c IncludeLines:true Name:vidtv_psi_desc_assign]
Results: map[SourceCode: 626: void vidtv_psi_desc_assign(struct vidtv_psi_desc **to,
627: struct vidtv_psi_desc *desc)
628: {
629: if (desc == *to)
630: return;
631:
632: if (*to)
633: vidtv_psi_desc_destroy(*to);
634:
635: *to = desc;
636: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_psi.c]
|
| 50/2 |
2026/05/17 05:26 |
llm |
expert |
0m
Model:
Tokens:
input: 33694
output: 52
thoughts: 1591
Thoughts: **Analyzing Descriptor Cloning and Identifying a Memory Leak**
Okay, so `vidtv_psi_desc_assign` handles replacing descriptors. I need to focus on how `vidtv_psi_desc_clone` works, as it seems relevant. Let's dig into that function's logic.
Ah, here's the core. It iterates through the existing descriptors, cloning each one. It looks like it's handling different descriptor types like `SERVICE_DESCRIPTOR` and `SHORT_EVENT_DESCRIPTOR`. The `vidtv_psi_short_event_desc_init` function is key here. It appears to append the new descriptor to the head of the list *within* its own logic! It calls `vidtv_psi_desc_chain` internally. Then the calling function does `prev->next = curr` again. This is redundant, but doesn't seem harmful.
Let's trace this carefully: if the `head` is not NULL, `vidtv_psi_short_event_desc_init` traverses to the end and appends. But wait, it also returns `curr`. Alright, I think I see it.
Okay, let's say the list has `D1` and `D2`.
- In the first iteration, `head` is NULL, so `curr = vidtv_psi_short_event_desc_init(NULL, ...)` is called. The descriptor (`D1'`) is allocated, `head` becomes `D1'`, and `prev` becomes `D1'`.
- In the second iteration, `head` is `D1'`. Then `curr = vidtv_psi_short_event_desc_init(head, ...)` is called. The new descriptor (`D2'`) is allocated, and the `vidtv_psi_desc_chain(head, D2')` function appends `D2'` to `D1'`. `vidtv_psi_short_event_desc_init` returns `D2'`. Back in `vidtv_psi_desc_clone`, `curr` is set to `D2'`, and everything seems fine.
So I don't see any obvious leaks or incorrect pointer assignments here, from my initial analysis. Let's see that leak report again.
Aha! It's leaking the `event_name` allocated inside `vidtv_psi_short_event_desc_init`. The backtrace shows `vidtv_psi_short_event_desc_init`, called from `vidtv_channel_s302m_init`, which in turn is called from `vidtv_channels_init`. So the leak is happening *after* the `vidtv_psi_desc_clone` operation, probably when it returns from there. We're not cleaning up the memory allocated in `vidtv_psi_short_event_desc_init` in some cases. It's not a leak in the cloning logic itself, but in the handling of what's cloned, I think.
|
| 51/2 |
2026/05/17 05:27 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_channel.c IncludeLines:true Name:vidtv_channels_init]
Results: map[SourceCode: 521: int vidtv_channels_init(struct vidtv_mux *m)
522: {
523: /* this is the place to add new 'channels' for vidtv */
524: m->channels = vidtv_channel_s302m_init(NULL, m->transport_stream_id);
525:
526: if (!m->channels)
527: return -ENOMEM;
528:
529: return 0;
530: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_channel.c]
|
| 52/2 |
2026/05/17 05:27 |
llm |
expert |
0m
Model:
Tokens:
input: 36169
output: 52
thoughts: 1317
Thoughts: **Analyzing Potential Memory Leaks in the `vidtv` Driver**
Okay, let's break this down. First, `m->channels` gets initialized via `vidtv_channel_s302m_init`, and then `vidtv_channel_si_init(m)` is called. The crucial point is the error handling: if `vidtv_channel_si_init` fails, `free_channels` is called, which then destroys the channels using `vidtv_channels_destroy(m)`. The initial leak report seems to point to `vidtv_channel_s302m_init`, so the concern is whether `vidtv_channels_destroy` cleans up what `vidtv_channel_s302m_init` allocates.
Looking at `vidtv_channels_destroy`, I see it iterates through the channels and calls destruction routines for various PSI sections like SDT, PAT, PMT, and EIT. Specifically, `vidtv_psi_eit_event_destroy` is called, which, in turn, calls `vidtv_psi_desc_destroy` for descriptors. This appears to free the descriptor contents, including `iso_language_code`, `event_name`, and `text` associated with `SHORT_EVENT_DESCRIPTOR`, so it *should* handle the memory allocated during the initialization of the channels. But, there is a leak reported!
Now, let's consider the subsequent leak reports. The stack traces point to these specific functions:
* `vidtv_psi_sdt_service_init` -> `vidtv_channel_sdt_serv_cat_into_new`
* `vidtv_psi_service_desc_init` -> `vidtv_psi_desc_clone` -> `vidtv_channel_sdt_serv_cat_into_new`
* `vidtv_psi_eit_event_init` -> `vidtv_channel_eit_event_cat_into_new`
These indicate that memory is being allocated during SDT and EIT service and event initializations. The traces suggest this happens *within* `vidtv_channel_si_init`. The critical point is: if `vidtv_channel_si_init` fails, memory allocated here should be freed, since `free_channels` is called. If it *succeeds*, the pointers are likely assigned to fields like `m->si.sdt`, `m->si.eit`, etc.
I have to consider how to free these structures. `vidtv_mux_destroy` calls `vidtv_channel_si_destroy(m)`. This frees the PSI tables. In particular, `vidtv_psi_sdt_table_destroy` is called, which destroys `sdt->service`, and `vidtv_psi_eit_table_destroy`, which destroys `eit->event`. This all *should* free the SDT and EIT entries, however, the leaks persist!
Why are they leaking? I have to consider whether `vidtv_mux_destroy` is always called when it is supposed to be. `vidtv_stop_streaming` calls it, which is called from `vidtv_stop_feed`. However, what happens if the file descriptor is closed without stopping the feed? I would expect this to be handled. I need to review what's called when a file descriptor is closed. The kernel `dvb_demux_release` *should* stop all feeds. I will look there for the problem.
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| 53/2 |
2026/05/17 05:27 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dvb_demux.c IncludeLines:true Name:dvb_demux_release]
Results: map[SourceCode:1243: static int dvb_demux_release(struct inode *inode, struct file *file)
1244: {
1245: struct dmxdev_filter *dmxdevfilter = file->private_data;
1246: struct dmxdev *dmxdev = dmxdevfilter->dev;
1247: int ret;
1248:
1249: ret = dvb_dmxdev_filter_free(dmxdev, dmxdevfilter);
1250:
1251: mutex_lock(&dmxdev->mutex);
1252: dmxdev->dvbdev->users--;
1253: if (dmxdev->dvbdev->users == 1 && dmxdev->exit == 1) {
1254: mutex_unlock(&dmxdev->mutex);
1255: wake_up(&dmxdev->dvbdev->wait_queue);
1256: } else
1257: mutex_unlock(&dmxdev->mutex);
1258:
1259: return ret;
1260: }
SourceFile:drivers/media/dvb-core/dmxdev.c]
|
| 54/2 |
2026/05/17 05:27 |
llm |
expert |
0m
Model:
Tokens:
input: 38624
output: 53
thoughts: 27
Thoughts: Here's a summary of my thought process, as requested:
**Diving into the DVB Demux Code**
Okay, so I'm digging into this DVB demux code, and I've hit a point where I need to understand the interaction between filter management and stopping filters. Specifically, I see that the function `dvb_dmxdev_filter_free` is responsible for freeing up a demux filter, but that this function *also* calls `dvb_dmxdev_filter_stop`. That's a key observation.
I need to understand the implications of this. Why is the stopping action coupled with freeing the filter's resources? Is this designed to ensure clean state transitions before memory is deallocated? Or is this part of some broader state machine? What are the synchronization guarantees around the stop and free actions? I need to look closely at the implementation of `dvb_dmxdev_filter_stop`, and *especially* how it affects shared resources the filter might be using. I need to make sure I don't introduce a race condition by freeing resources before the stop has fully completed, or introduce resource leaks if the stop process fails and resources are not released correctly.
|
| 55/2 |
2026/05/17 05:27 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dmxdev.c IncludeLines:true Name:dvb_dmxdev_filter_free]
Results: map[SourceCode: 846: static int dvb_dmxdev_filter_free(struct dmxdev *dmxdev,
847: struct dmxdev_filter *dmxdevfilter)
848: {
849: mutex_lock(&dmxdev->mutex);
850: mutex_lock(&dmxdevfilter->mutex);
851: if (dvb_vb2_is_streaming(&dmxdevfilter->vb2_ctx))
852: dvb_vb2_stream_off(&dmxdevfilter->vb2_ctx);
853: dvb_vb2_release(&dmxdevfilter->vb2_ctx);
854:
855:
856: dvb_dmxdev_filter_stop(dmxdevfilter);
857: dvb_dmxdev_filter_reset(dmxdevfilter);
858:
859: if (dmxdevfilter->buffer.data) {
860: void *mem = dmxdevfilter->buffer.data;
861:
862: spin_lock_irq(&dmxdev->lock);
863: dmxdevfilter->buffer.data = NULL;
864: spin_unlock_irq(&dmxdev->lock);
865: vfree(mem);
866: }
867:
868: dvb_dmxdev_filter_state_set(dmxdevfilter, DMXDEV_STATE_FREE);
869: wake_up(&dmxdevfilter->buffer.queue);
870: mutex_unlock(&dmxdevfilter->mutex);
871: mutex_unlock(&dmxdev->mutex);
872: return 0;
873: }
SourceFile:drivers/media/dvb-core/dmxdev.c]
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| 56/2 |
2026/05/17 05:27 |
llm |
expert |
0m
Model:
Tokens:
input: 39473
output: 53
thoughts: 26
Thoughts: Okay, here's my interpretation of that snippet, delivered as a first-person expert summary:
**Digging into DVB Filter Control**
Alright, so I'm looking at how this DVB filter is being managed. My understanding is that when `dvb_dmxdev_filter_stop` is called, it triggers a chain reaction. Specifically, it seems designed to call `dvb_dmxdev_feed_stop`. This makes immediate sense from an architectural perspective. The filter likely represents a specific data stream or a section within a broader transport stream. Stopping the filter, in essence, is the logical action that I'd expect to shut down whatever feed or data acquisition process that the filter was responsible for. I can infer this stop action potentially unregisters associated hardware resources, de-allocates buffers, or signals other DVB subsystems that the filter's data is no longer needed, reducing potential overhead and allowing for reuse of the hardware resources that they use. The relationship makes a clean, understandable design, I’d want to verify how the data is handled between these two calls - is data flushed, is the feed stopped immediately, or in a controlled way? The details of *that* interaction are likely key.
|
| 57/2 |
2026/05/17 05:27 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dmxdev.c IncludeLines:true Name:dvb_dmxdev_filter_stop]
Results: map[SourceCode: 551: static int dvb_dmxdev_filter_stop(struct dmxdev_filter *dmxdevfilter)
552: {
553: struct dmxdev_feed *feed;
554: struct dmx_demux *demux;
555:
556: if (dmxdevfilter->state < DMXDEV_STATE_GO)
557: return 0;
558:
559: switch (dmxdevfilter->type) {
560: case DMXDEV_TYPE_SEC:
561: if (!dmxdevfilter->feed.sec)
562: break;
563: dvb_dmxdev_feed_stop(dmxdevfilter);
564: if (dmxdevfilter->filter.sec)
565: dmxdevfilter->feed.sec->
566: release_filter(dmxdevfilter->feed.sec,
567: dmxdevfilter->filter.sec);
568: dvb_dmxdev_feed_restart(dmxdevfilter);
569: dmxdevfilter->feed.sec = NULL;
570: break;
571: case DMXDEV_TYPE_PES:
572: dvb_dmxdev_feed_stop(dmxdevfilter);
573: demux = dmxdevfilter->dev->demux;
574: list_for_each_entry(feed, &dmxdevfilter->feed.ts, next) {
575: demux->release_ts_feed(demux, feed->ts);
576: feed->ts = NULL;
577: }
578: break;
579: default:
580: if (dmxdevfilter->state == DMXDEV_STATE_ALLOCATED)
581: return 0;
582: return -EINVAL;
583: }
584:
585: dvb_ringbuffer_flush(&dmxdevfilter->buffer);
586: return 0;
587: }
SourceFile:drivers/media/dvb-core/dmxdev.c]
|
| 58/2 |
2026/05/17 05:27 |
llm |
expert |
0m
Model:
Tokens:
input: 40426
output: 53
thoughts: 28
Thoughts: Okay, here's my interpretation of that thought process, from an expert's perspective:
**Diving into the DVB Demux Feed Stop**
Alright, so I'm thinking about the DVB demux device feed stopping process. Specifically, I'm focusing on the call to `dvb_dmxdev_feed_stop`. That function, as I recall, is responsible for gracefully terminating a data feed. And that call is *really* important because I see that it initiates a critical cascade. `dvb_dmxdev_feed_stop` calls `feed->ts->stop_filtering(feed->ts)`. That "stop_filtering" function on `feed->ts` is the heart of the matter. It's the point where we're telling the transport stream filter associated with the feed, to, well, *stop* doing its filtering. This action is critical to free resources, shut down any processing that was underway, and prevent any further data from being passed up the stack. It's the final signal to cut the connection, so to speak. Understanding this flow is key to debugging feed issues and optimizing the shutdown process. I need to keep this relationship in mind as I start to debug issues with the DVB demux.
|
| 59/2 |
2026/05/17 05:27 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dmxdev.c IncludeLines:true Name:dvb_dmxdev_feed_stop]
Results: map[SourceCode: 480: /* stop feed but only mark the specified filter as stopped (state set) */
481: static int dvb_dmxdev_feed_stop(struct dmxdev_filter *dmxdevfilter)
482: {
483: struct dmxdev_feed *feed;
484:
485: dvb_dmxdev_filter_state_set(dmxdevfilter, DMXDEV_STATE_SET);
486:
487: switch (dmxdevfilter->type) {
488: case DMXDEV_TYPE_SEC:
489: timer_delete(&dmxdevfilter->timer);
490: dmxdevfilter->feed.sec->stop_filtering(dmxdevfilter->feed.sec);
491: break;
492: case DMXDEV_TYPE_PES:
493: list_for_each_entry(feed, &dmxdevfilter->feed.ts, next)
494: feed->ts->stop_filtering(feed->ts);
495: break;
496: default:
497: return -EINVAL;
498: }
499: return 0;
500: }
SourceFile:drivers/media/dvb-core/dmxdev.c]
|
| 60/2 |
2026/05/17 05:27 |
llm |
expert |
0m
Model:
Tokens:
input: 41145
output: 55
thoughts: 19
Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and presented as if it were my own internal monologue:
**Focusing in on `stop_filtering`**
Alright, let's zero in on this `stop_filtering` variable. I'm seeing it's being assigned to `dmx_ts_feed_stop_filtering`. That's a direct connection, which immediately suggests a specific function or process tied to our DMX Transport Stream feed is handling the filtering cessation. I'm inferring this likely means a shutdown of a filter or set of filters we are using on the feed. Perhaps we're explicitly disabling the processing of specific packets, or shutting down the whole filtering process? This is a crucial point in the flow, I want to confirm that I understand what is stopping and what this will mean. I'll need to know which filters are stopped by this command and what the implications of the stop are.
|
| 61/2 |
2026/05/17 05:27 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dvb_demux.c IncludeLines:true Name:dmx_ts_feed_stop_filtering]
Results: map[SourceCode: 762: static int dmx_ts_feed_stop_filtering(struct dmx_ts_feed *ts_feed)
763: {
764: struct dvb_demux_feed *feed = (struct dvb_demux_feed *)ts_feed;
765: struct dvb_demux *demux = feed->demux;
766: int ret;
767:
768: mutex_lock(&demux->mutex);
769:
770: if (feed->state < DMX_STATE_GO) {
771: mutex_unlock(&demux->mutex);
772: return -EINVAL;
773: }
774:
775: if (!demux->stop_feed) {
776: mutex_unlock(&demux->mutex);
777: return -ENODEV;
778: }
779:
780: ret = demux->stop_feed(feed);
781:
782: spin_lock_irq(&demux->lock);
783: ts_feed->is_filtering = 0;
784: feed->state = DMX_STATE_ALLOCATED;
785: spin_unlock_irq(&demux->lock);
786: mutex_unlock(&demux->mutex);
787:
788: return ret;
789: }
SourceFile:drivers/media/dvb-core/dvb_demux.c]
|
| 62/2 |
2026/05/17 05:27 |
llm |
expert |
0m
Model:
Tokens:
input: 41860
output: 55
thoughts: 512
Thoughts: **Analyzing the `vidtv` Demux Feed Lifecycle**
Okay, so I'm digging into this `vidtv` driver's demux feed handling. I see that `demux->stop_feed` is assigned to `vidtv_stop_feed`. The crucial bit here is that `vidtv_stop_feed` *decrements* `dvb->nfeeds`. That variable appears to be a feed counter. If `dvb->nfeeds` goes to zero, the code then calls `vidtv_stop_streaming`. Makes sense, right? Stop the underlying streaming when there are no more active feeds.
But hang on… what happens if the *start* operation fails? Let's trace that. Looking at `vidtv_start_feed`, I can see that `dvb->nfeeds` gets *incremented* right at the beginning. Then, *if* this is the first feed (`dvb->nfeeds == 1`), it calls `vidtv_start_streaming`. If `vidtv_start_streaming` fails, the return value `ret` (likely an error code like `-ENOMEM`) gets assigned to `rc`.
The kicker is that `dvb->nfeeds` is already incremented *before* the check for `vidtv_start_streaming` success. So, if `vidtv_start_streaming` fails, `vidtv_start_feed` will return the error code, but `dvb->nfeeds` will be left incremented. This means that `dvb_demux` *might not* call `stop_feed` in case of error. This is a potential resource leak: the demux might think there's a feed when there isn't, and `vidtv_stop_streaming` won't be called correctly. I need to check `dmx_ts_feed_start_filtering` to confirm this assumption. This needs a closer look, as if this is the case, there's a potential bug.
|
| 63/2 |
2026/05/17 05:27 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dvb_demux.c IncludeLines:true Name:dmx_ts_feed_start_filtering]
Results: map[SourceCode: 728: static int dmx_ts_feed_start_filtering(struct dmx_ts_feed *ts_feed)
729: {
730: struct dvb_demux_feed *feed = (struct dvb_demux_feed *)ts_feed;
731: struct dvb_demux *demux = feed->demux;
732: int ret;
733:
734: if (mutex_lock_interruptible(&demux->mutex))
735: return -ERESTARTSYS;
736:
737: if (feed->state != DMX_STATE_READY || feed->type != DMX_TYPE_TS) {
738: mutex_unlock(&demux->mutex);
739: return -EINVAL;
740: }
741:
742: if (!demux->start_feed) {
743: mutex_unlock(&demux->mutex);
744: return -ENODEV;
745: }
746:
747: ret = demux->start_feed(feed);
748: if (ret < 0) {
749: mutex_unlock(&demux->mutex);
750: return ret;
751: }
752:
753: spin_lock_irq(&demux->lock);
754: ts_feed->is_filtering = 1;
755: feed->state = DMX_STATE_GO;
756: spin_unlock_irq(&demux->lock);
757: mutex_unlock(&demux->mutex);
758:
759: return 0;
760: }
SourceFile:drivers/media/dvb-core/dvb_demux.c]
|
| 64/2 |
2026/05/17 05:27 |
llm |
expert |
0m
Model:
Tokens:
input: 43375
output: 53
thoughts: 191
Thoughts: **Analyzing the DVB Demux Filtering Start Sequence**
Okay, let me break this down. My initial thought process was straightforward: an error bubbling up. If `demux->start_feed` returns an error, that error propagates directly up through `dmx_ts_feed_start_filtering`, then `dvb_dmxdev_start_feed`, and finally `dvb_dmxdev_filter_start`. Simple error propagation, right?
The question then was, does the system clean up? Does it call `stop_feed` if there's an error? No, that can't be, because `feed->state` remains at `DMX_STATE_READY`. That makes sense. We don't want to prematurely shut down something if an error occurs. The assumption must be that `stop_feed` is handled elsewhere - most likely during a close operation.
Then I paused. Wait a second... Here's where it gets interesting. `dvb_dmxdev_filter_start` sets `dmxdevfilter->state = DMXDEV_STATE_GO` *before* it even calls `dvb_dmxdev_start_feed`. This is significant! Because of that, the state of the filter is changed before even the start of the feed! This will have implications down the line - I'll have to keep this in mind when I assess the stop process.
|
| 65/2 |
2026/05/17 05:28 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dmxdev.c IncludeLines:true Name:dvb_dmxdev_filter_start]
Results: map[SourceCode: 667: static int dvb_dmxdev_filter_start(struct dmxdev_filter *filter)
668: {
669: struct dmxdev *dmxdev = filter->dev;
670: struct dmxdev_feed *feed;
671: void *mem;
672: int ret, i;
673:
674: if (filter->state < DMXDEV_STATE_SET)
675: return -EINVAL;
676:
677: if (filter->state >= DMXDEV_STATE_GO)
678: dvb_dmxdev_filter_stop(filter);
679:
680: if (!filter->buffer.data) {
681: mem = vmalloc(filter->buffer.size);
682: if (!mem)
683: return -ENOMEM;
684: spin_lock_irq(&filter->dev->lock);
685: filter->buffer.data = mem;
686: spin_unlock_irq(&filter->dev->lock);
687: }
688:
689: dvb_ringbuffer_flush(&filter->buffer);
690:
691: switch (filter->type) {
692: case DMXDEV_TYPE_SEC:
693: {
694: struct dmx_sct_filter_params *para = &filter->params.sec;
695: struct dmx_section_filter **secfilter = &filter->filter.sec;
696: struct dmx_section_feed **secfeed = &filter->feed.sec;
697:
698: *secfilter = NULL;
699: *secfeed = NULL;
700:
701:
702: /* find active filter/feed with same PID */
703: for (i = 0; i < dmxdev->filternum; i++) {
704: if (dmxdev->filter[i].state >= DMXDEV_STATE_GO &&
705: dmxdev->filter[i].type == DMXDEV_TYPE_SEC &&
706: dmxdev->filter[i].params.sec.pid == para->pid) {
707: *secfeed = dmxdev->filter[i].feed.sec;
708: break;
709: }
710: }
711:
712: /* if no feed found, try to allocate new one */
713: if (!*secfeed) {
714: ret = dmxdev->demux->allocate_section_feed(dmxdev->demux,
715: secfeed,
716: dvb_dmxdev_section_callback);
717: if (!*secfeed) {
718: pr_err("DVB (%s): could not alloc feed\n",
719: __func__);
720: return ret;
721: }
722:
723: ret = (*secfeed)->set(*secfeed, para->pid,
724: (para->flags & DMX_CHECK_CRC) ? 1 : 0);
725: if (ret < 0) {
726: pr_err("DVB (%s): could not set feed\n",
727: __func__);
728: dvb_dmxdev_feed_restart(filter);
729: return ret;
730: }
731: } else {
732: dvb_dmxdev_feed_stop(filter);
733: }
734:
735: ret = (*secfeed)->allocate_filter(*secfeed, secfilter);
736: if (ret < 0) {
737: dvb_dmxdev_feed_restart(filter);
738: *secfeed = NULL;
739: dprintk("could not get filter\n");
740: return ret;
741: }
742:
743: (*secfilter)->priv = filter;
744:
745: memcpy(&((*secfilter)->filter_value[3]),
746: &(para->filter.filter[1]), DMX_FILTER_SIZE - 1);
747: memcpy(&(*secfilter)->filter_mask[3],
748: ¶->filter.mask[1], DMX_FILTER_SIZE - 1);
749: memcpy(&(*secfilter)->filter_mode[3],
750: ¶->filter.mode[1], DMX_FILTER_SIZE - 1);
751:
752: (*secfilter)->filter_value[0] = para->filter.filter[0];
753: (*secfilter)->filter_mask[0] = para->filter.mask[0];
754: (*secfilter)->filter_mode[0] = para->filter.mode[0];
755: (*secfilter)->filter_mask[1] = 0;
756: (*secfilter)->filter_mask[2] = 0;
757:
758: filter->todo = 0;
759:
760: ret = filter->feed.sec->start_filtering(filter->feed.sec);
761: if (ret < 0)
762: return ret;
763:
764: dvb_dmxdev_filter_timer(filter);
765: break;
766: }
767: case DMXDEV_TYPE_PES:
768: list_for_each_entry(feed, &filter->feed.ts, next) {
769: ret = dvb_dmxdev_start_feed(dmxdev, filter, feed);
770: if (ret < 0) {
771: dvb_dmxdev_filter_stop(filter);
772: return ret;
773: }
774: }
775: break;
776: default:
777: return -EINVAL;
778: }
779:
780: dvb_dmxdev_filter_state_set(filter, DMXDEV_STATE_GO);
781: return 0;
782: }
SourceFile:drivers/media/dvb-core/dmxdev.c]
|
| 66/2 |
2026/05/17 05:28 |
llm |
expert |
0m
Model:
Tokens:
input: 45732
output: 53
thoughts: 279
Thoughts: **A Critical Flaw in the DVB Demux Filter State Management**
Okay, so I'm looking at this `dvb_dmxdev_filter_start` function, and it's calling `dvb_dmxdev_start_feed`. That makes sense. But hang on... if `dvb_dmxdev_start_feed` returns an error, it calls `dvb_dmxdev_filter_stop(filter)`. That's standard error handling, good.
But here's where things get interesting, or rather, *wrong*. The state of the `filter` is still `DMXDEV_STATE_SET`! I can see that clearly. The problem is that `dvb_dmxdev_filter_state_set(filter, DMXDEV_STATE_GO)` is called *at the end* of `dvb_dmxdev_filter_start`. This is a potential race condition and logic error!
This means that `dvb_dmxdev_filter_stop`, in its current implementation, will effectively *do nothing* after a failure during `dvb_dmxdev_start_feed`. It immediately returns 0 because `filter->state < DMXDEV_STATE_GO`. The `filter` is never properly stopped.
Essentially, if `dvb_dmxdev_start_feed` fails, `dvb_dmxdev_filter_stop` is a no-op! That's a serious bug. I need to trace `dvb_dmxdev_start_feed` and figure out what might be causing failures and how that interacts with state management. This is definitely a code path that needs immediate attention.
|
| 67/2 |
2026/05/17 05:28 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dmxdev.c IncludeLines:true Name:dvb_dmxdev_start_feed]
Results: map[SourceCode: 615: static int dvb_dmxdev_start_feed(struct dmxdev *dmxdev,
616: struct dmxdev_filter *filter,
617: struct dmxdev_feed *feed)
618: {
619: ktime_t timeout = ktime_set(0, 0);
620: struct dmx_pes_filter_params *para = &filter->params.pes;
621: enum dmx_output otype;
622: int ret;
623: int ts_type;
624: enum dmx_ts_pes ts_pes;
625: struct dmx_ts_feed *tsfeed;
626:
627: feed->ts = NULL;
628: otype = para->output;
629:
630: ts_pes = para->pes_type;
631:
632: if (ts_pes < DMX_PES_OTHER)
633: ts_type = TS_DECODER;
634: else
635: ts_type = 0;
636:
637: if (otype == DMX_OUT_TS_TAP)
638: ts_type |= TS_PACKET;
639: else if (otype == DMX_OUT_TSDEMUX_TAP)
640: ts_type |= TS_PACKET | TS_DEMUX;
641: else if (otype == DMX_OUT_TAP)
642: ts_type |= TS_PACKET | TS_DEMUX | TS_PAYLOAD_ONLY;
643:
644: ret = dmxdev->demux->allocate_ts_feed(dmxdev->demux, &feed->ts,
645: dvb_dmxdev_ts_callback);
646: if (ret < 0)
647: return ret;
648:
649: tsfeed = feed->ts;
650: tsfeed->priv = filter;
651:
652: ret = tsfeed->set(tsfeed, feed->pid, ts_type, ts_pes, timeout);
653: if (ret < 0) {
654: dmxdev->demux->release_ts_feed(dmxdev->demux, tsfeed);
655: return ret;
656: }
657:
658: ret = tsfeed->start_filtering(tsfeed);
659: if (ret < 0) {
660: dmxdev->demux->release_ts_feed(dmxdev->demux, tsfeed);
661: return ret;
662: }
663:
664: return 0;
665: }
SourceFile:drivers/media/dvb-core/dmxdev.c]
|
| 68/2 |
2026/05/17 05:28 |
llm |
expert |
0m
Model:
Tokens:
input: 47251
output: 53
thoughts: 52
Thoughts: Here's my summary, as the expert:
**Understanding the DVB Feed Lifecycle**
Okay, so I'm digging into this DVB code, specifically how the transport stream (TS) feeds are managed. I'm seeing that there's this critical function, `tsfeed->start_filtering`, which, if it fails to initiate the filtering process, causes a crucial cleanup. The key is in how it cleans up. It looks like `dvb_dmxdev_start_feed` then calls `release_ts_feed`. Now, I have to remember this is the same as the function `dmx_ts_feed_release`. It is important that I note the relationship between these two functions in the call stack for the overall process of release. This is where I'll need to double-check error handling. This is a very important relationship.
|
| 69/2 |
2026/05/17 05:28 |
tool |
codesearch-definition-source |
0m
Error:
Args: map[ContextFile:drivers/media/dvb-core/dvb_demux.c IncludeLines:true Name:dmx_ts_feed_release]
Results: map[SourceCode: SourceFile:]
|
| 70/2 |
2026/05/17 05:28 |
llm |
expert |
0m
Model:
Tokens:
input: 47559
output: 19
thoughts: 22
Thoughts: Okay, here's my thought process summarized as requested:
**Finding the `release_ts_feed` Function**
Alright, I need to track down where this `release_ts_feed` function is defined and used. My instinct is to start within the `dvb_demux.c` file – that's the logical place given the name. Let's get cracking and do a quick search within that file to see what we can find. I expect it'll be a fairly straightforward process, but you never know what kind of legacy code we are dealing with. Let's get to it!
|
| 71/2 |
2026/05/17 05:28 |
tool |
grepper |
0m
Args: map[Expression:release_ts_feed]
Results: map[Output:drivers/media/dvb-core/dmxdev.c=551=static int dvb_dmxdev_filter_stop(struct dmxdev_filter *dmxdevfilter)
--
drivers/media/dvb-core/dmxdev.c-574- list_for_each_entry(feed, &dmxdevfilter->feed.ts, next) {
drivers/media/dvb-core/dmxdev.c:575: demux->release_ts_feed(demux, feed->ts);
drivers/media/dvb-core/dmxdev.c-576- feed->ts = NULL;
--
drivers/media/dvb-core/dmxdev.c=615=static int dvb_dmxdev_start_feed(struct dmxdev *dmxdev,
--
drivers/media/dvb-core/dmxdev.c-653- if (ret < 0) {
drivers/media/dvb-core/dmxdev.c:654: dmxdev->demux->release_ts_feed(dmxdev->demux, tsfeed);
drivers/media/dvb-core/dmxdev.c-655- return ret;
--
drivers/media/dvb-core/dmxdev.c-659- if (ret < 0) {
drivers/media/dvb-core/dmxdev.c:660: dmxdev->demux->release_ts_feed(dmxdev->demux, tsfeed);
drivers/media/dvb-core/dmxdev.c-661- return ret;
--
drivers/media/dvb-core/dmxdev.c=910=static int dvb_dmxdev_remove_pid(struct dmxdev *dmxdev,
--
drivers/media/dvb-core/dmxdev.c-921- feed->ts->stop_filtering(feed->ts);
drivers/media/dvb-core/dmxdev.c:922: filter->dev->demux->release_ts_feed(filter->dev->demux,
drivers/media/dvb-core/dmxdev.c-923- feed->ts);
--
drivers/media/dvb-core/dvb_demux.c=791=static int dvbdmx_allocate_ts_feed(struct dmx_demux *dmx,
--
drivers/media/dvb-core/dvb_demux.c-837-
drivers/media/dvb-core/dvb_demux.c:838:static int dvbdmx_release_ts_feed(struct dmx_demux *dmx,
drivers/media/dvb-core/dvb_demux.c-839- struct dmx_ts_feed *ts_feed)
--
drivers/media/dvb-core/dvb_demux.c=1240=int dvb_dmx_init(struct dvb_demux *dvbdemux)
--
drivers/media/dvb-core/dvb_demux.c-1297- dmx->allocate_ts_feed = dvbdmx_allocate_ts_feed;
drivers/media/dvb-core/dvb_demux.c:1298: dmx->release_ts_feed = dvbdmx_release_ts_feed;
drivers/media/dvb-core/dvb_demux.c-1299- dmx->allocate_section_feed = dvbdmx_allocate_section_feed;
--
drivers/media/dvb-core/dvb_net.c=1053=static int dvb_net_feed_start(struct net_device *dev)
--
drivers/media/dvb-core/dvb_net.c-1137- pr_err("%s: could not set ts feed\n", dev->name);
drivers/media/dvb-core/dvb_net.c:1138: priv->demux->release_ts_feed(priv->demux, priv->tsfeed);
drivers/media/dvb-core/dvb_net.c-1139- priv->tsfeed = NULL;
--
drivers/media/dvb-core/dvb_net.c=1153=static int dvb_net_feed_stop(struct net_device *dev)
--
drivers/media/dvb-core/dvb_net.c-1192- }
drivers/media/dvb-core/dvb_net.c:1193: priv->demux->release_ts_feed(priv->demux, priv->tsfeed);
drivers/media/dvb-core/dvb_net.c-1194- priv->tsfeed = NULL;
--
include/media/demux.h=350=enum dmx_demux_caps {
--
include/media/demux.h-440- *
include/media/demux.h:441: * @release_ts_feed: Releases the resources allocated with @allocate_ts_feed.
include/media/demux.h-442- * Any filtering in progress on the TS feed should be stopped before
--
include/media/demux.h=560=struct dmx_demux {
--
include/media/demux.h-570- dmx_ts_cb callback);
include/media/demux.h:571: int (*release_ts_feed)(struct dmx_demux *demux,
include/media/demux.h-572- struct dmx_ts_feed *feed);
]
|
| 72/2 |
2026/05/17 05:28 |
llm |
expert |
0m
Model:
Tokens:
input: 49123
output: 54
thoughts: 15
Thoughts: Okay, here's my interpretation of that thought process, assuming I'm an expert in this field, presented as a first-person summary:
**Analyzing `dvbdmx_release_ts_feed`**
Alright, let's break down this function: `dvbdmx_release_ts_feed`. My immediate thought is, what's its purpose? Given the naming convention, it's pretty clear we're dealing with DVB (Digital Video Broadcasting) and a transport stream (TS) feed. The "release" part suggests we're likely dealing with some kind of resource management, perhaps freeing up a specific TS feed that was previously acquired or allocated by the system. My experience tells me this is probably a function that works in conjunction with a `dvbdmx_acquire_ts_feed` or similar function, handling the lifecycle of a TS feed within a DVB demuxer context. I'll need to know the surrounding code, context, and data structures involved to be certain, but the naming is quite indicative. I'd expect it to handle things like decrementing reference counts, closing associated file descriptors or network sockets, freeing allocated buffers, and possibly signaling the DVB device that the feed is no longer in use. I'd pay close attention to potential mutex locks or synchronization primitives used here to ensure proper thread safety and prevent race conditions. I'd be looking for things like error handling – what happens if the feed isn't actually acquired, or if there are unexpected states? Overall, it's a critical function for resource management and preventing memory leaks or device contention within a DVB system.
|
| 73/2 |
2026/05/17 05:28 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dvb_demux.c IncludeLines:true Name:dvbdmx_release_ts_feed]
Results: map[SourceCode: 838: static int dvbdmx_release_ts_feed(struct dmx_demux *dmx,
839: struct dmx_ts_feed *ts_feed)
840: {
841: struct dvb_demux *demux = (struct dvb_demux *)dmx;
842: struct dvb_demux_feed *feed = (struct dvb_demux_feed *)ts_feed;
843:
844: mutex_lock(&demux->mutex);
845:
846: if (feed->state == DMX_STATE_FREE) {
847: mutex_unlock(&demux->mutex);
848: return -EINVAL;
849: }
850:
851: feed->state = DMX_STATE_FREE;
852: feed->filter->state = DMX_STATE_FREE;
853:
854: dvb_demux_feed_del(feed);
855:
856: feed->pid = 0xffff;
857:
858: if (feed->ts_type & TS_DECODER && feed->pes_type < DMX_PES_OTHER)
859: demux->pesfilter[feed->pes_type] = NULL;
860:
861: mutex_unlock(&demux->mutex);
862: return 0;
863: }
SourceFile:drivers/media/dvb-core/dvb_demux.c]
|
| 74/2 |
2026/05/17 05:28 |
llm |
expert |
0m
Model:
Tokens:
input: 49973
output: 52
thoughts: 608
Thoughts: **Debugging a Potential Resource Leak**
Okay, so I'm tracing the feed startup process here, and something feels off. My initial thought was that `dvbdmx_release_ts_feed` would call `stop_feed`, but it doesn't. That's the first red flag. Now, let's follow the control flow. If `dmx_ts_feed_start_filtering` fails, it returns an error. `dvb_dmxdev_start_feed` then calls `release_ts_feed`, which makes sense. However, `dmx_ts_feed_start_filtering` calls `demux->start_feed(feed)`. If *that* fails, it also returns the error, which is handled correctly with the mutex unlock and return.
The trouble, I think, is inside `vidtv_start_feed`. It increments `dvb->nfeeds` *before* the call to `vidtv_start_streaming`. Now, if `vidtv_start_streaming` fails, `rc` gets set to `ret`, the error code, which is good. But, `dvb->nfeeds` *remains* incremented! So the return value of `vidtv_start_feed` is `rc`, which is negative (the error code). And `dmx_ts_feed_start_filtering` returns that same negative value.
Then `dvb_dmxdev_start_feed` calls `release_ts_feed`. `release_ts_feed` correctly sets `feed->state = DMX_STATE_FREE` and cleans up the feed, but it STILL doesn't call `stop_feed`! Meaning, `dvb->nfeeds` stays at 1. Since `dvb->nfeeds` is 1, `vidtv_stop_feed` will NEVER be called for that feed. Because the feed is essentially released.
This strongly suggests a potential resource leak. If `vidtv_start_streaming` fails, we have an incremented `nfeeds` and no corresponding decrement. If it fails, does it leak `dvb->mux`? Now I need to check `vidtv_start_streaming` to confirm that. I need to see what it's doing with `dvb->mux` and ensure any allocated resources are properly freed even in the error case. I need to be sure this isn't creating an orphaned state.
|
| 75/2 |
2026/05/17 05:28 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_bridge.c IncludeLines:true Name:vidtv_start_streaming]
Results: map[SourceCode: 166: static int vidtv_start_streaming(struct vidtv_dvb *dvb)
167: {
168: struct vidtv_mux_init_args mux_args = {
169: .mux_rate_kbytes_sec = mux_rate_kbytes_sec,
170: .on_new_packets_available_cb = vidtv_bridge_on_new_pkts_avail,
171: .pcr_period_usecs = pcr_period_msec * USEC_PER_MSEC,
172: .si_period_usecs = si_period_msec * USEC_PER_MSEC,
173: .pcr_pid = pcr_pid,
174: .transport_stream_id = VIDTV_DEFAULT_TS_ID,
175: .network_id = VIDTV_DEFAULT_NETWORK_ID,
176: .network_name = VIDTV_DEFAULT_NETWORK_NAME,
177: .priv = dvb,
178: };
179: struct device *dev = &dvb->pdev->dev;
180: u32 mux_buf_sz;
181:
182: if (dvb->streaming) {
183: dev_warn_ratelimited(dev, "Already streaming. Skipping.\n");
184: return 0;
185: }
186:
187: if (mux_buf_sz_pkts)
188: mux_buf_sz = mux_buf_sz_pkts;
189: else
190: mux_buf_sz = vidtv_bridge_mux_buf_sz_for_mux_rate();
191:
192: mux_args.mux_buf_sz = mux_buf_sz;
193:
194: dvb->mux = vidtv_mux_init(dvb->fe[0], dev, &mux_args);
195: if (!dvb->mux)
196: return -ENOMEM;
197:
198: dvb->streaming = true;
199: vidtv_mux_start_thread(dvb->mux);
200:
201: dev_dbg_ratelimited(dev, "Started streaming\n");
202: return 0;
203: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_bridge.c]
|
| 76/2 |
2026/05/17 05:28 |
llm |
expert |
0m
Model:
Tokens:
input: 51856
output: 52
thoughts: 112
Thoughts: **Debugging a Suspected Memory Leak**
Okay, hold on a second. Something isn't adding up here. If `vidtv_mux_init` fails, it's supposed to return NULL. Then, down the line, `vidtv_start_streaming` is throwing an `-ENOMEM` error, which seems suspicious. But the leak report specifically says `vidtv_mux_init` *succeeds* in allocating the `vidtv_channel_s302m_init` and `vidtv_channel_si_init` structs! That should mean the allocations are happening as expected, right?
Wait a minute... could `vidtv_mux_init` be failing *later* on in its process, *after* those initial allocations, and then freeing something as part of its cleanup? That would explain the inconsistent error reporting and the apparent success/failure dichotomy. Alright, I need to get back in there and double-check the `vidtv_mux_init` function itself. Let's see what's actually going on in there...
|
| 77/2 |
2026/05/17 05:28 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/test-drivers/vidtv/vidtv_mux.c IncludeLines:true Name:vidtv_mux_init]
Results: map[SourceCode: 477: struct vidtv_mux *vidtv_mux_init(struct dvb_frontend *fe,
478: struct device *dev,
479: struct vidtv_mux_init_args *args)
480: {
481: struct vidtv_mux *m;
482:
483: m = kzalloc_obj(*m);
484: if (!m)
485: return NULL;
486:
487: m->dev = dev;
488: m->fe = fe;
489: m->timing.pcr_period_usecs = args->pcr_period_usecs;
490: m->timing.si_period_usecs = args->si_period_usecs;
491:
492: m->mux_rate_kbytes_sec = args->mux_rate_kbytes_sec;
493:
494: m->on_new_packets_available_cb = args->on_new_packets_available_cb;
495:
496: m->mux_buf = vzalloc(args->mux_buf_sz);
497: if (!m->mux_buf)
498: goto free_mux;
499:
500: m->mux_buf_sz = args->mux_buf_sz;
501:
502: m->pcr_pid = args->pcr_pid;
503: m->transport_stream_id = args->transport_stream_id;
504: m->priv = args->priv;
505: m->network_id = args->network_id;
506: m->network_name = kstrdup(args->network_name, GFP_KERNEL);
507: if (!m->network_name)
508: goto free_mux_buf;
509:
510: m->timing.current_jiffies = get_jiffies_64();
511:
512: if (args->channels)
513: m->channels = args->channels;
514: else
515: if (vidtv_channels_init(m) < 0)
516: goto free_mux_network_name;
517:
518: /* will alloc data for pmt_sections after initializing pat */
519: if (vidtv_channel_si_init(m) < 0)
520: goto free_channels;
521:
522: INIT_WORK(&m->mpeg_thread, vidtv_mux_tick);
523:
524: if (vidtv_mux_pid_ctx_init(m) < 0)
525: goto free_channel_si;
526:
527: return m;
528:
529: free_channel_si:
530: vidtv_channel_si_destroy(m);
531: free_channels:
532: vidtv_channels_destroy(m);
533: free_mux_network_name:
534: kfree(m->network_name);
535: free_mux_buf:
536: vfree(m->mux_buf);
537: free_mux:
538: kfree(m);
539: return NULL;
540: }
SourceFile:drivers/media/test-drivers/vidtv/vidtv_mux.c]
|
| 78/2 |
2026/05/17 05:28 |
llm |
expert |
0m
Model:
Tokens:
input: 53243
output: 53
thoughts: 241
Thoughts: **Debugging a Memory Leak in a DVB Streaming Pipeline**
Okay, so I'm digging into this memory leak. The trace indicates that if `vidtv_mux_pid_ctx_init(m)` fails, it's supposed to clean up its mess by calling `vidtv_channel_si_destroy(m)` and `vidtv_channels_destroy(m)`. That makes sense; it allocates, it frees. Standard defensive programming.
But if `vidtv_mux_pid_ctx_init` *succeeds*, it looks like it hands back `m`, right? And the subsequent calls – `vidtv_start_streaming`, `vidtv_start_feed`, `dmx_ts_feed_start_filtering`, `dvb_dmxdev_start_feed`, and `dvb_dmxdev_filter_start` – all return 0, 1, and then 0, 0, and 0 respectively. No errors reported! So, by all indications, the happy path is operating as designed.
So, where's the leak? It has to be something that *doesn't* happen. My gut tells me something is not being cleaned up. And then it hits me! `vidtv_stop_streaming` is never called! That's the likely culprit.
Now, the question is *why* isn't `vidtv_stop_streaming` being called? It has to be triggered somewhere up the call stack, so let's start by looking at `dvb_dmxdev_filter_stop`. That's where I'll find my answer.
|
| 79/2 |
2026/05/17 05:28 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dmxdev.c IncludeLines:true Name:dvb_dmxdev_filter_stop]
Results: map[SourceCode: 551: static int dvb_dmxdev_filter_stop(struct dmxdev_filter *dmxdevfilter)
552: {
553: struct dmxdev_feed *feed;
554: struct dmx_demux *demux;
555:
556: if (dmxdevfilter->state < DMXDEV_STATE_GO)
557: return 0;
558:
559: switch (dmxdevfilter->type) {
560: case DMXDEV_TYPE_SEC:
561: if (!dmxdevfilter->feed.sec)
562: break;
563: dvb_dmxdev_feed_stop(dmxdevfilter);
564: if (dmxdevfilter->filter.sec)
565: dmxdevfilter->feed.sec->
566: release_filter(dmxdevfilter->feed.sec,
567: dmxdevfilter->filter.sec);
568: dvb_dmxdev_feed_restart(dmxdevfilter);
569: dmxdevfilter->feed.sec = NULL;
570: break;
571: case DMXDEV_TYPE_PES:
572: dvb_dmxdev_feed_stop(dmxdevfilter);
573: demux = dmxdevfilter->dev->demux;
574: list_for_each_entry(feed, &dmxdevfilter->feed.ts, next) {
575: demux->release_ts_feed(demux, feed->ts);
576: feed->ts = NULL;
577: }
578: break;
579: default:
580: if (dmxdevfilter->state == DMXDEV_STATE_ALLOCATED)
581: return 0;
582: return -EINVAL;
583: }
584:
585: dvb_ringbuffer_flush(&dmxdevfilter->buffer);
586: return 0;
587: }
SourceFile:drivers/media/dvb-core/dmxdev.c]
|
| 80/2 |
2026/05/17 05:28 |
llm |
expert |
0m
Model:
Tokens:
input: 54507
output: 53
thoughts: 480
Thoughts: **Debugging a DVB Demuxing Issue**
Okay, let me trace this. I see that `dvb_dmxdev_filter_stop` is supposed to be called, which in turn calls `dvb_dmxdev_feed_stop`. That cascades into `feed->ts->stop_filtering(feed->ts)`, which ultimately resolves to `demux->stop_feed(feed)`. And *that* is `vidtv_stop_feed`. This function should decrement `dvb->nfeeds` and, if it hits zero, it should call `vidtv_stop_streaming`. So, in a properly functioning scenario, `vidtv_stop_streaming` *should* be invoked.
Now, hold on. What if `dvb_dmxdev_filter_stop` *isn't* called? That's the critical question. I remember it's called from `dvb_dmxdev_filter_free`, and *that* is called from `dvb_demux_release`. So, closing the file descriptor should trigger that sequence.
But wait, looking at this reproducer code… the `ioctl` calls... specifically the call to `DVB_DEMUX_DMX_ADD_PID`. That's where it's adding a PID to the filter. Let's dig into `dvb_dmxdev_add_pid` and see how this interacts with the rest of the chain. This is likely the key to finding what's gone awry.
|
| 81/2 |
2026/05/17 05:28 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dmxdev.c IncludeLines:true Name:dvb_dmxdev_add_pid]
Results: map[SourceCode: 883: static int dvb_dmxdev_add_pid(struct dmxdev *dmxdev,
884: struct dmxdev_filter *filter, u16 pid)
885: {
886: struct dmxdev_feed *feed;
887:
888: if ((filter->type != DMXDEV_TYPE_PES) ||
889: (filter->state < DMXDEV_STATE_SET))
890: return -EINVAL;
891:
892: /* only TS packet filters may have multiple PIDs */
893: if ((filter->params.pes.output != DMX_OUT_TSDEMUX_TAP) &&
894: (!list_empty(&filter->feed.ts)))
895: return -EINVAL;
896:
897: feed = kzalloc_obj(struct dmxdev_feed);
898: if (feed == NULL)
899: return -ENOMEM;
900:
901: feed->pid = pid;
902: list_add(&feed->next, &filter->feed.ts);
903:
904: if (filter->state >= DMXDEV_STATE_GO)
905: return dvb_dmxdev_start_feed(dmxdev, filter, feed);
906:
907: return 0;
908: }
SourceFile:drivers/media/dvb-core/dmxdev.c]
|
| 82/2 |
2026/05/17 05:28 |
llm |
expert |
0m
Model:
Tokens:
input: 55799
output: 53
thoughts: 1216
Thoughts: **Analysis of a Potential Resource Leak in the DVB Demux Driver**
Okay, so I've been tracing the logic in `dvb_dmxdev_add_pid` and its interaction with the demux driver. It looks like a feed is added to `filter->feed.ts`. Then, when a `DMX_START` command comes in, `dvb_dmxdev_filter_start` is called.
The problem seems to be here: if `dvb_dmxdev_start_feed` fails for a *subsequent* feed in a filter (say, after the first one started successfully), `dvb_dmxdev_filter_stop` is called. But, and here's the catch, the `filter->state` *isn't* `DMXDEV_STATE_GO` yet because `dvb_dmxdev_filter_state_set(filter, DMXDEV_STATE_GO)` is only called at the *end* of `dvb_dmxdev_filter_start`. So `dvb_dmxdev_filter_stop` immediately returns 0 because `filter->state` is still less than `DMXDEV_STATE_GO`.
Effectively, if `dvb_dmxdev_start_feed` fails for ANY feed, `dvb_dmxdev_filter_stop` does *nothing*. The feeds that *did* start successfully are *never* stopped. This leaves `dvb->nfeeds` greater than 0, even after a "stop" attempt.
Then, when the file descriptor is closed (or when the filter is freed), `dvb_dmxdev_filter_free` calls `dvb_dmxdev_filter_stop` again. And again, `dmxdevfilter->state` is STILL `DMXDEV_STATE_SET`. So `dvb_dmxdev_filter_stop` *again* returns 0! The feeds are *still* never stopped! This means `vidtv_stop_streaming` is *never* called, `vidtv_mux_destroy` is *never* called, and any memory allocated in `vidtv_mux_init` *leaks*. This is a critical resource leak!
Let me verify this: if `filter->feed.ts` contains two feeds (for instance, created with two `DMX_ADD_PID` ioctls), the first might start without a problem. `dvb_dmxdev_start_feed` returns 0. If the second feed fails to start, `dvb_dmxdev_start_feed` returns an error (`< 0`). The code then calls `dvb_dmxdev_filter_stop(filter)`. But `filter->state` is still `DMXDEV_STATE_SET`, which is less than `DMXDEV_STATE_GO`. `dvb_dmxdev_filter_stop` then immediately returns 0! So the first feed continues running, even though the overall operation failed. The userspace gets an error, closes the fd, which leads to `dvb_demux_release`, and thus to `dvb_dmxdev_filter_free`. `dvb_dmxdev_filter_free` calls `dvb_dmxdev_filter_stop`, but again, since filter state is still SET, that function does nothing. The filter gets freed, but the first feed *continues running* in the demux! The call to `dvb_dmxdev_filter_stop` is followed by a call to `dvb_dmxdev_filter_reset`.
|
| 83/2 |
2026/05/17 05:29 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dmxdev.c IncludeLines:true Name:dvb_dmxdev_filter_reset]
Results: map[SourceCode: 602: static inline int dvb_dmxdev_filter_reset(struct dmxdev_filter *dmxdevfilter)
603: {
604: if (dmxdevfilter->state < DMXDEV_STATE_SET)
605: return 0;
606:
607: if (dmxdevfilter->type == DMXDEV_TYPE_PES)
608: dvb_dmxdev_delete_pids(dmxdevfilter);
609:
610: dmxdevfilter->type = DMXDEV_TYPE_NONE;
611: dvb_dmxdev_filter_state_set(dmxdevfilter, DMXDEV_STATE_ALLOCATED);
612: return 0;
613: }
SourceFile:drivers/media/dvb-core/dmxdev.c]
|
| 84/2 |
2026/05/17 05:29 |
llm |
expert |
0m
Model:
Tokens:
input: 58103
output: 54
thoughts: 18
Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and presented as if it were my own internal monologue:
**Focusing on Feed Management in DVB Drivers**
Alright, so we're talking about DVB driver internals, specifically concerning PID (Packet Identifier) management within the demux (demultiplexer) context. The key function here, `dvb_dmxdev_delete_pids`, is the one responsible for the cleanup, which makes me think of the cleanup operation. It's clear that this function isn't just *managing* the PIDs; it's actively *deleting* the feeds associated with them. This is the crucial point for proper resource management and avoiding memory leaks within the DVB subsystem, as it is used to delete and release the feeds. It is important to remember to avoid memory leaks.
|
| 85/2 |
2026/05/17 05:29 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dmxdev.c IncludeLines:true Name:dvb_dmxdev_delete_pids]
Results: map[SourceCode: 589: static void dvb_dmxdev_delete_pids(struct dmxdev_filter *dmxdevfilter)
590: {
591: struct dmxdev_feed *feed, *tmp;
592:
593: /* delete all PIDs */
594: list_for_each_entry_safe(feed, tmp, &dmxdevfilter->feed.ts, next) {
595: list_del(&feed->next);
596: kfree(feed);
597: }
598:
599: BUG_ON(!list_empty(&dmxdevfilter->feed.ts));
600: }
SourceFile:drivers/media/dvb-core/dmxdev.c]
|
| 86/2 |
2026/05/17 05:29 |
llm |
expert |
0m
Model:
Tokens:
input: 58583
output: 54
thoughts: 1049
Thoughts: **Analyzing a DVB Demux Memory Leak**
Okay, so I've been looking at this DVB demux code, and I think I've found a critical issue. My initial thought was that `dvb_dmxdev_delete_pids` was supposed to handle freeing everything, but it's clear now that it *only* frees the `dmxdev_feed` structs. It doesn't call `release_ts_feed` or `stop_filtering` as it should! This is a problem.
That means the `dmx_ts_feed` struct that's allocated within `dvb_dmxdev_start_feed` is leaking memory. And on top of that, `vidtv_start_streaming` is never being stopped properly.
Let me refresh my memory of `dvb_dmxdev_start_feed`. Okay, here's the relevant section:
```c
ret = dmxdev->demux->allocate_ts_feed(dmxdev->demux, &feed->ts,
dvb_dmxdev_ts_callback);
if (ret < 0)
return ret;
tsfeed = feed->ts;
tsfeed->priv = filter;
ret = tsfeed->set(tsfeed, feed->pid, ts_type, ts_pes, timeout);
if (ret < 0) {
dmxdev->demux->release_ts_feed(dmxdev->demux, tsfeed);
return ret;
}
ret = tsfeed->start_filtering(tsfeed);
if (ret < 0) {
dmxdev->demux->release_ts_feed(dmxdev->demux, tsfeed);
return ret;
}
```
So, if `dvb_dmxdev_start_feed` succeeds, `feed->ts` is allocated, its parameters set and the filtering is started.
Crucially, if *any* of the steps in starting the *second* feed fails (e.g., `allocate_ts_feed`, `set`, or `start_filtering`), the function returns an error. This is a crucial point. That error propagates up to the user.
Now let's see, if `dvb_dmxdev_start_feed` fails... `dvb_dmxdev_filter_start` gets called. `dvb_dmxdev_filter_start` tries to call `dvb_dmxdev_filter_stop(filter)`. But `dvb_dmxdev_filter_stop` does absolutely *nothing* because `filter->state` isn't yet in the `DMXDEV_STATE_GO` state. So it's effectively a no-op. So the failed call to `dvb_dmxdev_filter_start` returns `< 0`.
Then, the user closes the file descriptor.
Now, `dvb_dmxdev_filter_free` is called, which calls `dvb_dmxdev_filter_stop` (still a no-op). Then, it calls `dvb_dmxdev_filter_reset`. `dvb_dmxdev_filter_reset` calls `dvb_dmxdev_delete_pids`. And we're back where we started: `dvb_dmxdev_delete_pids` only frees the `dmxdev_feed` structs, but *never* frees `feed->ts` (the `dmx_ts_feed`)! It also *never* calls `stop_filtering`! The same goes for the never decrementing `dvb->nfeeds`, so `vidtv_stop_streaming` is never called. So, the `vidtv_mux` is leaked!
Aha! This perfectly explains the memory leak! The `dmx_ts_feed` isn't properly released, and the relevant cleanup functions aren't called.
Now, how could the second feed fail to start? That's what I need to figure out. Let's look at the reproducer:
```c
// ioctl$DVB_DEMUX_DMX_SET_PES_FILTER arguments: [
...
syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0x40146f2c, /*arg=*/0x200000000000ul);
// ioctl$DVB_DEMUX_DMX_ADD_PID arguments: [
...
syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0x40
|
| 87/2 |
2026/05/17 05:29 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dvb_demux.c IncludeLines:true Name:dvbdmx_allocate_ts_feed]
Results: map[SourceCode: 791: static int dvbdmx_allocate_ts_feed(struct dmx_demux *dmx,
792: struct dmx_ts_feed **ts_feed,
793: dmx_ts_cb callback)
794: {
795: struct dvb_demux *demux = (struct dvb_demux *)dmx;
796: struct dvb_demux_feed *feed;
797:
798: if (mutex_lock_interruptible(&demux->mutex))
799: return -ERESTARTSYS;
800:
801: feed = dvb_dmx_feed_alloc(demux);
802: if (!feed) {
803: mutex_unlock(&demux->mutex);
804: return -EBUSY;
805: }
806:
807: feed->type = DMX_TYPE_TS;
808: feed->cb.ts = callback;
809: feed->demux = demux;
810: feed->pid = 0xffff;
811: feed->peslen = 0xfffa;
812: feed->buffer_flags = 0;
813:
814: (*ts_feed) = &feed->feed.ts;
815: (*ts_feed)->parent = dmx;
816: (*ts_feed)->priv = NULL;
817: (*ts_feed)->is_filtering = 0;
818: (*ts_feed)->start_filtering = dmx_ts_feed_start_filtering;
819: (*ts_feed)->stop_filtering = dmx_ts_feed_stop_filtering;
820: (*ts_feed)->set = dmx_ts_feed_set;
821:
822: feed->filter = dvb_dmx_filter_alloc(demux);
823: if (!feed->filter) {
824: feed->state = DMX_STATE_FREE;
825: mutex_unlock(&demux->mutex);
826: return -EBUSY;
827: }
828:
829: feed->filter->type = DMX_TYPE_TS;
830: feed->filter->feed = feed;
831: feed->filter->state = DMX_STATE_READY;
832:
833: mutex_unlock(&demux->mutex);
834:
835: return 0;
836: }
SourceFile:drivers/media/dvb-core/dvb_demux.c]
|
| 88/2 |
2026/05/17 05:29 |
llm |
expert |
0m
Model:
Tokens:
input: 61459
output: 53
thoughts: 25
Thoughts: Okay, here's my interpretation of those thoughts, framed as my own:
**Investigating a Potential DVB Demux Feed Allocation Failure**
Alright, I'm stuck, and I need to figure out what's going wrong. My initial thought is that the `dvb_dmx_feed_alloc` function might be the culprit. Perhaps it's failing to allocate the necessary resources for the demux feed. That's a classic place to start when dealing with DVB setups, especially with allocation-related errors. Or, another potential snag could be that there's an issue with the `tsfeed->set` method. I need to check the return values of both these crucial operations. It might be that the initial allocation is ok, but setting the transport stream feed fails because the parameters are wrong. I need to make sure to eliminate both of those potential causes, and then consider other possibilities. I need to delve into the error handling and status checks associated with these functions to get to the bottom of this.
|
| 89/2 |
2026/05/17 05:29 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dvb_demux.c IncludeLines:true Name:dmx_ts_feed_set]
Results: map[SourceCode: 687: static int dmx_ts_feed_set(struct dmx_ts_feed *ts_feed, u16 pid, int ts_type,
688: enum dmx_ts_pes pes_type, ktime_t timeout)
689: {
690: struct dvb_demux_feed *feed = (struct dvb_demux_feed *)ts_feed;
691: struct dvb_demux *demux = feed->demux;
692:
693: if (pid > DMX_MAX_PID)
694: return -EINVAL;
695:
696: if (mutex_lock_interruptible(&demux->mutex))
697: return -ERESTARTSYS;
698:
699: if (ts_type & TS_DECODER) {
700: if (pes_type >= DMX_PES_OTHER) {
701: mutex_unlock(&demux->mutex);
702: return -EINVAL;
703: }
704:
705: if (demux->pesfilter[pes_type] &&
706: demux->pesfilter[pes_type] != feed) {
707: mutex_unlock(&demux->mutex);
708: return -EINVAL;
709: }
710:
711: demux->pesfilter[pes_type] = feed;
712: demux->pids[pes_type] = pid;
713: }
714:
715: dvb_demux_feed_add(feed);
716:
717: feed->pid = pid;
718: feed->timeout = timeout;
719: feed->ts_type = ts_type;
720: feed->pes_type = pes_type;
721:
722: feed->state = DMX_STATE_READY;
723: mutex_unlock(&demux->mutex);
724:
725: return 0;
726: }
SourceFile:drivers/media/dvb-core/dvb_demux.c]
|
| 90/2 |
2026/05/17 05:29 |
llm |
expert |
0m
Model:
Tokens:
input: 62379
output: 53
thoughts: 1978
Thoughts: **DVB Demux Memory Leak Analysis**
Alright, let's break this down. It seems there's a serious issue within the DVB demux framework, specifically related to how PES filters are handled and how feeds are started and stopped. The core problem lies within `dvb_dmxdev_filter_start` and, critically, the interaction with `dvb_dmxdev_filter_stop`.
Here's the sequence: the `dmx_ts_feed_set` function has a vital check: if a `TS_DECODER` feed tries to use a `pes_type` already associated with another feed, it returns `-EINVAL`. This is triggered in the reproducer, where one feed is set with `SET_PES_FILTER` (setting `demux->pesfilter[5]` with `feed1`) and a second feed tries to use the *same* `pes_type` (5) via `ADD_PID` (`feed2`), resulting in `-EINVAL`. This is understandable.
The critical issue is how `dvb_dmxdev_filter_start` reacts to this error. `dvb_dmxdev_start_feed` fails, returning -EINVAL. It should then call `dvb_dmxdev_filter_stop` to clean up. But `dvb_dmxdev_filter_stop` does nothing because `filter->state` is not `DMXDEV_STATE_GO`. This leaves the first feed running and it’s never stopped. This results in the memory allocated by `vidtv_mux_init` remaining allocated and leaking.
The bug is in the *interaction* between `dvb_dmxdev_filter_start` and `dvb_dmxdev_filter_stop`. `dvb_dmxdev_filter_start` could set `filter->state` to `DMXDEV_STATE_GO` BEFORE it starts the feeds, or, more robustly, it could manually stop already started feeds. Or it could allow the `dvb_dmxdev_filter_stop` to stop the feeds regardless of `filter->state`.
Further investigation of `dvb_dmxdev_filter_stop` shows that it does have the mechanism to stop feeds, but the conditional check short-circuits it. The more concerning issue is `dvb_dmxdev_filter_free`, which calls `dvb_dmxdev_filter_stop`. If it runs, the list of feeds in `filter->feed.ts` is traversed and all feeds are released. It’s like the `release_ts_feed` is supposed to clean up the underlying driver’s resources. But because of the check, `dvb_dmxdev_filter_stop` is never called, so `release_ts_feed` is never called.
Okay, let's confirm the leak: the issue is a memory leak of the `dmx_ts_feed` and what the driver allocated. `dvb_dmxdev_delete_pids` is called when removing the filter, and this frees the `dmxdev_feed` struct *which contains a pointer to* the `dmx_ts_feed`. But the *contents* of the `dmx_ts_feed` which points to the underlying demux memory (in this case, `vidtv_mux`) is NOT freed. The function `release_ts_feed` is never called on the allocated feed.
Now, is this exploitable? It’s a denial-of-service vulnerability due to the memory leak. But *can* it cause a use-after-free? This is a possibility. The `dmx_ts_feed` itself is still running and could call the callback `dvb_dmxdev_ts_callback`! This is where things get interesting… let's see what that callback does.
|
| 91/2 |
2026/05/17 05:29 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dmxdev.c IncludeLines:true Name:dvb_dmxdev_ts_callback]
Results: map[SourceCode: 425: static int dvb_dmxdev_ts_callback(const u8 *buffer1, size_t buffer1_len,
426: const u8 *buffer2, size_t buffer2_len,
427: struct dmx_ts_feed *feed,
428: u32 *buffer_flags)
429: {
430: struct dmxdev_filter *dmxdevfilter = feed->priv;
431: struct dvb_ringbuffer *buffer;
432: #ifdef CONFIG_DVB_MMAP
433: struct dvb_vb2_ctx *ctx;
434: #endif
435: int ret;
436:
437: spin_lock(&dmxdevfilter->dev->lock);
438: if (dmxdevfilter->params.pes.output == DMX_OUT_DECODER) {
439: spin_unlock(&dmxdevfilter->dev->lock);
440: return 0;
441: }
442:
443: if (dmxdevfilter->params.pes.output == DMX_OUT_TAP ||
444: dmxdevfilter->params.pes.output == DMX_OUT_TSDEMUX_TAP) {
445: buffer = &dmxdevfilter->buffer;
446: #ifdef CONFIG_DVB_MMAP
447: ctx = &dmxdevfilter->vb2_ctx;
448: #endif
449: } else {
450: buffer = &dmxdevfilter->dev->dvr_buffer;
451: #ifdef CONFIG_DVB_MMAP
452: ctx = &dmxdevfilter->dev->dvr_vb2_ctx;
453: #endif
454: }
455:
456: if (dvb_vb2_is_streaming(ctx)) {
457: ret = dvb_vb2_fill_buffer(ctx, buffer1, buffer1_len,
458: buffer_flags, false);
459: if (ret == buffer1_len)
460: ret = dvb_vb2_fill_buffer(ctx, buffer2, buffer2_len,
461: buffer_flags, false);
462: } else {
463: if (buffer->error) {
464: spin_unlock(&dmxdevfilter->dev->lock);
465: wake_up(&buffer->queue);
466: return 0;
467: }
468: ret = dvb_dmxdev_buffer_write(buffer, buffer1, buffer1_len);
469: if (ret == buffer1_len)
470: ret = dvb_dmxdev_buffer_write(buffer,
471: buffer2, buffer2_len);
472: }
473: if (ret < 0)
474: buffer->error = ret;
475: spin_unlock(&dmxdevfilter->dev->lock);
476: wake_up(&buffer->queue);
477: return 0;
478: }
SourceFile:drivers/media/dvb-core/dmxdev.c]
|
| 92/2 |
2026/05/17 05:29 |
llm |
expert |
0m
Model:
Tokens:
input: 66166
output: 53
thoughts: 648
Thoughts: **Analyzing a Potential Race Condition in the DVB Demux Driver**
Okay, let's break this down. I see that `feed->priv` is assigned `dmxdevfilter`, which is concerning. If the file is closed, `dvb_dmxdev_filter_free` is called, and this frees the filter...wait a minute, no it doesn't *actually* free the struct. It sets `dmxdevfilter->state = DMXDEV_STATE_FREE`. That's the key.
Looking closer, `dmxdevfilter` is actually allocated as an array *inside* the `dmxdev` struct. So the filter struct itself isn't freed. It's just marked as `FREE`. Ah, that's where the problem arises. If a filter is marked `FREE`, it can be reallocated by another `open` or `ioctl` call from *another process*! That's bad.
The old `dmx_ts_feed` is still happily running and calling `dvb_dmxdev_ts_callback` with `feed->priv = dmxdevfilter`. That callback is going to access things like `dmxdevfilter->buffer` and `dmxdevfilter->dev->lock`. If the new process reuses this filter for something else, then the original feed is going to corrupt the data and buffers belonging to the second process.
Is this a Use-After-Free scenario? Not quite. The `dmxdevfilter` is still valid as long as the device is registered. The potential vulnerability is a **data corruption** issue due to an aliased `dmxdevfilter` being used to process data from two different clients.
Now, wait a second, let me check `dvb_dmxdev_filter_free` again. Ah, I see it now. `dvb_dmxdev_filter_free` *does* free `dmxdevfilter->buffer.data` with `vfree(mem)`. The issue is, `dvb_dmxdev_ts_callback` later calls `dvb_dmxdev_buffer_write`, which writes to this potentially freed buffer. This confirms my hypothesis. This *is* a Use-After-Free condition. If the buffer is written to *after* being freed, we have a clear problem.
I need to investigate `dvb_dmxdev_buffer_write` now. It's the point of contact to write into the reallocated memory. This could cause some serious issues!
|
| 93/2 |
2026/05/17 05:30 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dmxdev.c IncludeLines:true Name:dvb_dmxdev_buffer_write]
Results: map[SourceCode: 34: static int dvb_dmxdev_buffer_write(struct dvb_ringbuffer *buf,
35: const u8 *src, size_t len)
36: {
37: ssize_t free;
38:
39: if (!len)
40: return 0;
41: if (!buf->data)
42: return 0;
43:
44: free = dvb_ringbuffer_free(buf);
45: if (len > free) {
46: dprintk("buffer overflow\n");
47: return -EOVERFLOW;
48: }
49:
50: return dvb_ringbuffer_write(buf, src, len);
51: }
SourceFile:drivers/media/dvb-core/dmxdev.c]
|
| 94/2 |
2026/05/17 05:30 |
llm |
expert |
1m
Model:
Tokens:
input: 67663
output: 52
thoughts: 408
Thoughts: **My Analysis of This Code**
Okay, so I'm looking at this code and immediately see a crucial check: `if (!buf->data) return 0;`. Seems straightforward enough, right? It's trying to prevent writing to a buffer that's been freed. However, a red flag pops up. What if *another* process gets allocated and sets `buf->data`? Suddenly, the old feed is going to write into the new process's memory space! That's a classic data leak and corruption vulnerability between processes. But, importantly, it's *not* a kernel-level use-after-free, since `buf->data` is valid memory.
Now, my mind races. What about when the `dmx_ts_feed` is actually freed? Is it ever released, or is it dangling? Let's trace it down. `dmx_ts_feed` is *inside* `dvb_demux_feed`, which itself is allocated through `dvb_dmx_feed_alloc`. I found the matching function, `dvbdmx_release_ts_feed`. Ah, great. But wait, `dvbdmx_release_ts_feed` is *never* called for the leaking feed! It seems like this `dvb_demux_feed` is getting leaked indefinitely. And consequently, so is the `vidtv_mux` structure.
Okay, let's step back. Does closing the demux device trigger the freeing of `dvb_demux_feed`? Time to check `dvb_demux_release`. The code there, `dvb_dmxdev_filter_free`, indicates that it only frees the filter. There doesn't appear to be any direct freeing of feeds here. So, what about when the adapter is unregistered? Does `dvb_dmx_release` handle freeing the feeds then? That's what I need to investigate next.
|
| 95/2 |
2026/05/17 05:31 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dvb_demux.c IncludeLines:true Name:dvb_dmx_release]
Results: map[SourceCode:1317: void dvb_dmx_release(struct dvb_demux *dvbdemux)
1318: {
1319: vfree(dvbdemux->cnt_storage);
1320: vfree(dvbdemux->filter);
1321: vfree(dvbdemux->feed);
1322: }
SourceFile:drivers/media/dvb-core/dvb_demux.c]
|
| 96/2 |
2026/05/17 05:31 |
llm |
expert |
0m
Model:
Tokens:
input: 68673
output: 54
thoughts: 100
Thoughts: Okay, let me break this down.
**Understanding the `dvbdemux->feed` Allocation**
Right, so I'm looking at this `dvbdemux->feed` structure. The code snippet makes it explicitly clear: it's an array. Not a dynamically allocated single instance, but a pre-allocated array of `dvb_demux_feed` structures, sized according to `dvbdemux->feednum`. They're using `vmalloc`, which is important to note - it means physically contiguous memory isn't guaranteed, though it's likely still in kernel space.
The crucial part is understanding this implies `dvb_dmx_feed_alloc` isn't doing individual `mallocs` or `kallocs` for each feed. Instead, it's operating on this pre-existing array, simply finding an available, unused entry within that array. That's a fundamental difference in the allocation strategy here. This changes how I need to think about resource management and potential concurrency issues. It's an important detail, particularly when considering potential allocation errors or cleanup.
|
| 97/2 |
2026/05/17 05:31 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/media/dvb-core/dvb_demux.c IncludeLines:true Name:dvb_dmx_feed_alloc]
Results: map[SourceCode: 632: static struct dvb_demux_feed *dvb_dmx_feed_alloc(struct dvb_demux *demux)
633: {
634: int i;
635:
636: for (i = 0; i < demux->feednum; i++)
637: if (demux->feed[i].state == DMX_STATE_FREE)
638: break;
639:
640: if (i == demux->feednum)
641: return NULL;
642:
643: demux->feed[i].state = DMX_STATE_ALLOCATED;
644:
645: return &demux->feed[i];
646: }
SourceFile:drivers/media/dvb-core/dvb_demux.c]
|
| 98/2 |
2026/05/17 05:31 |
llm |
expert |
0m
Model:
Tokens:
input: 69315
output: 66
thoughts: 4613
Thoughts: **Analysis of a DVB Demux Feed Leak**
Okay, so after digging into this `dvb_demux_feed` issue, I've got a pretty good handle on what's going on. The core problem is that when `dvb_dmxdev_start_feed` fails for a *second* feed within a single filter, the *first* feed isn't properly stopped. This leaves the feed in either `DMX_STATE_READY` or `DMX_STATE_GO`, effectively making it permanently occupied. Since the DVB subsystem has a limited number of feeds, this can be exploited to exhaust all available resources, which in essence is a resource leak – a Denial of Service.
Because the first feed isn't stopped, the associated resources, such as the `vidtv_mux` allocated in this test driver, also remain allocated. `vidtv_mux` itself dynamically allocates a substantial amount of memory for buffers and channels, and this contributes to a memory leak. Now, because this isn't a use-after-free situation, it's strictly a memory leak, meaning it *can* lead to an Out of Memory (OOM) situation and a denial of service, but it doesn't cause any memory corruption. Depending on the system's configuration, an OOM situation could lead to the system getting killed.
The good news is that the reproducer uses `/dev/dvb/adapter#/demux#`, which is typically accessible to unprivileged users within the `video` group or users with the right ACLs. The core issue lies within `dvb-core/dmxdev.c`, so it's not a driver-specific bug; it's a systemic flaw that affects any DVB driver that uses `dvb_dmxdev_start_feed`.
I've confirmed that `dvb_dmxdev_filter_stop` is, in fact, immediately returning if the filter isn't in the `DMXDEV_STATE_GO` state, which is precisely the situation when `dvb_dmxdev_start_feed` fails. The `DMX_STOP` ioctl also calls this function and thus doesn't fix it.
Yes, an unprivileged user can trigger this leak: they can open a demux device, configure a PES filter with a few PIDs, start it, and if starting the second feed fails, the first feed (and any driver allocated resources) is leaked. They can repeat this until all feeds are used, causing an OOM.
As for exploitation, this is *not* a privilege escalation vulnerability. The leaked memory isn't controllable, so there's no way to overwrite important kernel data. The only real effect is a DoS via resource exhaustion. If a new user reuses the same filter slot, they will inherit the stream data of the leaked feed in their buffers, but this is data leakage, not kernel memory corruption.
In this case, the main risk is resource exhaustion; repeatedly triggering the leak will exhaust kmalloc memory, eventually leading to a Denial of Service. While the `vidtv` driver is a test driver, the bug lies in `dvb-core` and can be exploited with any DVB driver.
|
| 99/2 |
2026/05/17 05:32 |
tool |
set-results |
0m
Args: map[DenialOfService:true Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:true UserNamespace:false VMGuestTrigger:false VMHostTrigger:false]
Results: map[DenialOfService:true Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:true UserNamespace:false VMGuestTrigger:false VMHostTrigger:false]
|
| 100/2 |
2026/05/17 05:32 |
llm |
expert |
1m
Model:
Tokens:
input: 74742
output: 809
thoughts: 13
Thoughts: Okay, here's the summary, rendered as a first-person thought process, aimed at an expert audience:
**Finalizing the Response**
Alright, the data's been crunched, the analysis is complete, and the interpretation has been rigorously checked. Everything’s in place, the variables have been accounted for, and any potential caveats have been addressed. Now it’s time to move beyond the internal review and prepare the final response. It's the point where I synthesize everything into a clear, concise, and defensible conclusion. No room for ambiguity here; this is the culmination of the process, the definitive statement based on solid evidence. I'm ready to present the final findings.
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2026/05/17 05:33 |
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Results: map[Explanation:The bug is a memory and resource leak in the core DVB demux subsystem
(`drivers/media/dvb-core/dmxdev.c`), which can be triggered by an unprivileged
user with access to the DVB demux device node (typically
`/dev/dvb/adapterX/demuxY`).
### Root Cause Analysis
The vulnerability occurs when starting a PES filter that has multiple PIDs
(feeds) attached to it.
1. The user configures a PES filter using the `DMX_SET_PES_FILTER` ioctl, which
adds the first PID to the filter's feed list.
2. The user adds a second PID to the same filter using the `DMX_ADD_PID` ioctl.
3. The user starts the filter using the `DMX_START` ioctl, which invokes
`dvb_dmxdev_filter_start()`.
4. `dvb_dmxdev_filter_start()` iterates over the filter's feed list and calls
`dvb_dmxdev_start_feed()` for each feed.
5. The first feed starts successfully, allocating underlying driver resources
(in this bug report, `vidtv_mux` and its associated structures).
6. The second feed fails to start (e.g., `dmx_ts_feed_set()` returns `-EINVAL`
because the `pes_type` is already in use by the first feed).
7. Upon failure, `dvb_dmxdev_filter_start()` attempts to clean up by calling
`dvb_dmxdev_filter_stop()`.
8. **The Bug:** `dvb_dmxdev_filter_stop()` contains a check `if
(dmxdevfilter->state < DMXDEV_STATE_GO) return 0;`. Because
`dvb_dmxdev_filter_start()` only updates the state to `DMXDEV_STATE_GO` at the
very end of the function (upon complete success), the state is still
`DMXDEV_STATE_SET`. Thus, `dvb_dmxdev_filter_stop()` returns immediately without
stopping the first feed.
9. The first feed is left running indefinitely. Even when the file descriptor is
closed, `dvb_dmxdev_filter_free()` calls `dvb_dmxdev_filter_stop()`, which again
does nothing. The filter is reset and its `dmxdev_feed` structs are freed, but
the underlying `dmx_ts_feed` and the hardware/driver resources are permanently
leaked.
### Security Impact
- **Denial of Service (DoS):** An attacker can repeatedly trigger this bug to
leak `dmx_ts_feed` slots and underlying driver memory (like `vidtv_mux` buffers
and structures). This will eventually exhaust the limited number of demux feeds
or system memory, leading to a Denial of Service (OOM).
- **Cross-Process Data Leak/Corruption:** Because the leaked feed continues to
run and holds a pointer to the freed filter slot, if another process opens the
demux device and reuses the same filter slot, the leaked feed will start writing
its TS packets into the new process's buffers.
- **Exploitable:** There is no memory corruption (Use-After-Free) in the kernel
itself because the buffer pointers are properly locked and checked before
writing, and the filter struct itself is not freed (it's part of a pre-allocated
array in the `dmxdev`). Thus, it is not exploitable for privilege escalation.
- **Unprivileged Access:** The `/dev/dvb/adapterX/demuxY` device nodes are
typically accessible to unprivileged users (e.g., users in the `video` group or
the active desktop user via ACLs).]
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