| 0/0 |
2026/05/17 00:45 |
flow |
assessment-security |
48m
Results: map[DenialOfService:false Explanation:Based on the analysis of the source code and the KMSAN report, here is the
assessment of the bug:
**Root Cause Analysis:**
The bug is a KMSAN uninitialized value report in `ntfs_iomap_begin`.
The uninitialized value is the local variable `lcn`, which is passed by
reference to `attr_data_get_block()`.
Inside `attr_data_get_block()`, if the requested virtual cluster number (`vcn`)
is not found in the run list (`run_lookup_entry` returns false) and the caller
did not request allocation of new clusters (`new == NULL`), the function sets
`*len = 0` and jumps to the `ok` label, returning `0` (success) without ever
initializing `*lcn`.
Back in `ntfs_iomap_begin()`, the uninitialized `lcn` is then used in a series
of comparisons:
```c
if (lcn == EOF_LCN) { ... }
...
if (lcn == RESIDENT_LCN) {
if (offset >= clen) { ... return -EFAULT; }
...
}
if (!clen) {
return -EINVAL;
}
```
**Security Impact:**
Although `lcn` is uninitialized, the variable `clen` (which corresponds to
`*len` set by `attr_data_get_block`) is guaranteed to be `0` in this specific
code path.
Because `clen` is `0`, the function will always end up returning an error:
- If `lcn` happens to match `RESIDENT_LCN`, it checks `offset >= clen`. Since
`offset` is a file offset (always `>= 0`) and `clen` is `0`, this condition is
always true, and the function returns `-EFAULT`.
- If `lcn` is anything else (or if it was `EOF_LCN` and got reassigned to
`SPARSE_LCN`), the code eventually reaches `if (!clen)`, which evaluates to
true, and returns `-EINVAL`.
In all cases, the uninitialized value does not influence the control flow in any
dangerous way. It is not used for memory accesses, pointer arithmetic, or leaked
to userspace. It simply results in a read error (`-EINVAL` or `-EFAULT`), which
gracefully propagates up the call stack and fails the operation (e.g., failing
the mount process).
Therefore, this is a **benign** uninitialized value use. It is **not
exploitable** and does **not cause a Denial of Service** (the kernel does not
crash or hang; it just rejects the corrupted filesystem).
**Reachability:**
The bug can be triggered by mounting a maliciously crafted NTFS filesystem image
where the run list does not cover the allocated size of a file.
However, the `ntfs3` filesystem does not have the `FS_USERNS_MOUNT` flag set in
its `file_system_type` definition. This means it cannot be mounted from within a
user namespace. Mounting it requires `CAP_SYS_ADMIN` in the initial user
namespace.
Thus, the bug is **not accessible from unprivileged processes** or **user
namespaces**. It can only be triggered if the root user explicitly mounts the
image, or if the system is configured to auto-mount external media (e.g., USB
drives on a Desktop environment), making it a **Peripheral / Malicious
Filesystem Trigger**. Exploitable:false FilesystemTrigger:true NetworkTrigger:false PeripheralTrigger:true RemoteTrigger:false Unprivileged:false UserNamespace:false VMGuestTrigger:false VMHostTrigger:false]
|
| 1/1 |
2026/05/17 00:45 |
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 <errno.h>
#include <fcntl.h>
#include <setjmp.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
#include <linux/loop.h>
#ifndef __NR_memfd_create
#define __NR_memfd_create 319
#endif
static unsigned long long procid;
//% This code is derived from puff.{c,h}, found in the zlib development. The
//% original files come with the following copyright notice:
//% Copyright (C) 2002-2013 Mark Adler, all rights reserved
//% version 2.3, 21 Jan 2013
//% This software is provided 'as-is', without any express or implied
//% warranty. In no event will the author be held liable for any damages
//% arising from the use of this software.
//% Permission is granted to anyone to use this software for any purpose,
//% including commercial applications, and to alter it and redistribute it
//% freely, subject to the following restrictions:
//% 1. The origin of this software must not be misrepresented; you must not
//% claim that you wrote the original software. If you use this software
//% in a product, an acknowledgment in the product documentation would be
//% appreciated but is not required.
//% 2. Altered source versions must be plainly marked as such, and must not be
//% misrepresented as being the original software.
//% 3. This notice may not be removed or altered from any source distribution.
//% Mark Adler madler@alumni.caltech.edu
//% BEGIN CODE DERIVED FROM puff.{c,h}
#define MAXBITS 15
#define MAXLCODES 286
#define MAXDCODES 30
#define MAXCODES (MAXLCODES + MAXDCODES)
#define FIXLCODES 288
struct puff_state {
unsigned char* out;
unsigned long outlen;
unsigned long outcnt;
const unsigned char* in;
unsigned long inlen;
unsigned long incnt;
int bitbuf;
int bitcnt;
jmp_buf env;
};
static int puff_bits(struct puff_state* s, int need)
{
long val = s->bitbuf;
while (s->bitcnt < need) {
if (s->incnt == s->inlen)
longjmp(s->env, 1);
val |= (long)(s->in[s->incnt++]) << s->bitcnt;
s->bitcnt += 8;
}
s->bitbuf = (int)(val >> need);
s->bitcnt -= need;
return (int)(val & ((1L << need) - 1));
}
static int puff_stored(struct puff_state* s)
{
s->bitbuf = 0;
s->bitcnt = 0;
if (s->incnt + 4 > s->inlen)
return 2;
unsigned len = s->in[s->incnt++];
len |= s->in[s->incnt++] << 8;
if (s->in[s->incnt++] != (~len & 0xff) ||
s->in[s->incnt++] != ((~len >> 8) & 0xff))
return -2;
if (s->incnt + len > s->inlen)
return 2;
if (s->outcnt + len > s->outlen)
return 1;
for (; len--; s->outcnt++, s->incnt++) {
if (s->in[s->incnt])
s->out[s->outcnt] = s->in[s->incnt];
}
return 0;
}
struct puff_huffman {
short* count;
short* symbol;
};
static int puff_decode(struct puff_state* s, const struct puff_huffman* h)
{
int first = 0;
int index = 0;
int bitbuf = s->bitbuf;
int left = s->bitcnt;
int code = first = index = 0;
int len = 1;
short* next = h->count + 1;
while (1) {
while (left--) {
code |= bitbuf & 1;
bitbuf >>= 1;
int count = *next++;
if (code - count < first) {
s->bitbuf = bitbuf;
s->bitcnt = (s->bitcnt - len) & 7;
return h->symbol[index + (code - first)];
}
index += count;
first += count;
first <<= 1;
code <<= 1;
len++;
}
left = (MAXBITS + 1) - len;
if (left == 0)
break;
if (s->incnt == s->inlen)
longjmp(s->env, 1);
bitbuf = s->in[s->incnt++];
if (left > 8)
left = 8;
}
return -10;
}
static int puff_construct(struct puff_huffman* h, const short* length, int n)
{
int len;
for (len = 0; len <= MAXBITS; len++)
h->count[len] = 0;
int symbol;
for (symbol = 0; symbol < n; symbol++)
(h->count[length[symbol]])++;
if (h->count[0] == n)
return 0;
int left = 1;
for (len = 1; len <= MAXBITS; len++) {
left <<= 1;
left -= h->count[len];
if (left < 0)
return left;
}
short offs[MAXBITS + 1];
offs[1] = 0;
for (len = 1; len < MAXBITS; len++)
offs[len + 1] = offs[len] + h->count[len];
for (symbol = 0; symbol < n; symbol++)
if (length[symbol] != 0)
h->symbol[offs[length[symbol]]++] = symbol;
return left;
}
static int puff_codes(struct puff_state* s,
const struct puff_huffman* lencode,
const struct puff_huffman* distcode)
{
static const short lens[29] = {
3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258};
static const short lext[29] = {
0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0};
static const short dists[30] = {
1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
8193, 12289, 16385, 24577};
static const short dext[30] = {
0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
12, 12, 13, 13};
int symbol;
do {
symbol = puff_decode(s, lencode);
if (symbol < 0)
return symbol;
if (symbol < 256) {
if (s->outcnt == s->outlen)
return 1;
if (symbol)
s->out[s->outcnt] = symbol;
s->outcnt++;
} else if (symbol > 256) {
symbol -= 257;
if (symbol >= 29)
return -10;
int len = lens[symbol] + puff_bits(s, lext[symbol]);
symbol = puff_decode(s, distcode);
if (symbol < 0)
return symbol;
unsigned dist = dists[symbol] + puff_bits(s, dext[symbol]);
if (dist > s->outcnt)
return -11;
if (s->outcnt + len > s->outlen)
return 1;
while (len--) {
if (dist <= s->outcnt && s->out[s->outcnt - dist])
s->out[s->outcnt] = s->out[s->outcnt - dist];
s->outcnt++;
}
}
} while (symbol != 256);
return 0;
}
static int puff_fixed(struct puff_state* s)
{
static int virgin = 1;
static short lencnt[MAXBITS + 1], lensym[FIXLCODES];
static short distcnt[MAXBITS + 1], distsym[MAXDCODES];
static struct puff_huffman lencode, distcode;
if (virgin) {
lencode.count = lencnt;
lencode.symbol = lensym;
distcode.count = distcnt;
distcode.symbol = distsym;
short lengths[FIXLCODES];
int symbol;
for (symbol = 0; symbol < 144; symbol++)
lengths[symbol] = 8;
for (; symbol < 256; symbol++)
lengths[symbol] = 9;
for (; symbol < 280; symbol++)
lengths[symbol] = 7;
for (; symbol < FIXLCODES; symbol++)
lengths[symbol] = 8;
puff_construct(&lencode, lengths, FIXLCODES);
for (symbol = 0; symbol < MAXDCODES; symbol++)
lengths[symbol] = 5;
puff_construct(&distcode, lengths, MAXDCODES);
virgin = 0;
}
return puff_codes(s, &lencode, &distcode);
}
static int puff_dynamic(struct puff_state* s)
{
static const short order[19] =
{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
int nlen = puff_bits(s, 5) + 257;
int ndist = puff_bits(s, 5) + 1;
int ncode = puff_bits(s, 4) + 4;
if (nlen > MAXLCODES || ndist > MAXDCODES)
return -3;
short lengths[MAXCODES];
int index;
for (index = 0; index < ncode; index++)
lengths[order[index]] = puff_bits(s, 3);
for (; index < 19; index++)
lengths[order[index]] = 0;
short lencnt[MAXBITS + 1], lensym[MAXLCODES];
struct puff_huffman lencode = {lencnt, lensym};
int err = puff_construct(&lencode, lengths, 19);
if (err != 0)
return -4;
index = 0;
while (index < nlen + ndist) {
int symbol;
int len;
symbol = puff_decode(s, &lencode);
if (symbol < 0)
return symbol;
if (symbol < 16)
lengths[index++] = symbol;
else {
len = 0;
if (symbol == 16) {
if (index == 0)
return -5;
len = lengths[index - 1];
symbol = 3 + puff_bits(s, 2);
} else if (symbol == 17)
symbol = 3 + puff_bits(s, 3);
else
symbol = 11 + puff_bits(s, 7);
if (index + symbol > nlen + ndist)
return -6;
while (symbol--)
lengths[index++] = len;
}
}
if (lengths[256] == 0)
return -9;
err = puff_construct(&lencode, lengths, nlen);
if (err && (err < 0 || nlen != lencode.count[0] + lencode.count[1]))
return -7;
short distcnt[MAXBITS + 1], distsym[MAXDCODES];
struct puff_huffman distcode = {distcnt, distsym};
err = puff_construct(&distcode, lengths + nlen, ndist);
if (err && (err < 0 || ndist != distcode.count[0] + distcode.count[1]))
return -8;
return puff_codes(s, &lencode, &distcode);
}
static int puff(
unsigned char* dest,
unsigned long* destlen,
const unsigned char* source,
unsigned long sourcelen)
{
struct puff_state s = {
.out = dest,
.outlen = *destlen,
.outcnt = 0,
.in = source,
.inlen = sourcelen,
.incnt = 0,
.bitbuf = 0,
.bitcnt = 0,
};
int err;
if (setjmp(s.env) != 0)
err = 2;
else {
int last;
do {
last = puff_bits(&s, 1);
int type = puff_bits(&s, 2);
err = type == 0 ? puff_stored(&s) : (type == 1 ? puff_fixed(&s) : (type == 2 ? puff_dynamic(&s) : -1));
if (err != 0)
break;
} while (!last);
}
*destlen = s.outcnt;
return err;
}
//% END CODE DERIVED FROM puff.{c,h}
#define ZLIB_HEADER_WIDTH 2
static int puff_zlib_to_file(const unsigned char* source, unsigned long sourcelen, int dest_fd)
{
if (sourcelen < ZLIB_HEADER_WIDTH)
return 0;
source += ZLIB_HEADER_WIDTH;
sourcelen -= ZLIB_HEADER_WIDTH;
const unsigned long max_destlen = 132 << 20;
void* ret = mmap(0, max_destlen, PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0);
if (ret == MAP_FAILED)
return -1;
unsigned char* dest = (unsigned char*)ret;
unsigned long destlen = max_destlen;
int err = puff(dest, &destlen, source, sourcelen);
if (err) {
munmap(dest, max_destlen);
errno = -err;
return -1;
}
if (write(dest_fd, dest, destlen) != (ssize_t)destlen) {
munmap(dest, max_destlen);
return -1;
}
return munmap(dest, max_destlen);
}
static int setup_loop_device(unsigned char* data, unsigned long size, const char* loopname, int* loopfd_p)
{
int err = 0, loopfd = -1;
int memfd = syscall(__NR_memfd_create, "syzkaller", 0);
if (memfd == -1) {
err = errno;
goto error;
}
if (puff_zlib_to_file(data, size, memfd)) {
err = errno;
goto error_close_memfd;
}
loopfd = open(loopname, O_RDWR);
if (loopfd == -1) {
err = errno;
goto error_close_memfd;
}
if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
if (errno != EBUSY) {
err = errno;
goto error_close_loop;
}
ioctl(loopfd, LOOP_CLR_FD, 0);
usleep(1000);
if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
err = errno;
goto error_close_loop;
}
}
close(memfd);
*loopfd_p = loopfd;
return 0;
error_close_loop:
close(loopfd);
error_close_memfd:
close(memfd);
error:
errno = err;
return -1;
}
static void reset_loop_device(const char* loopname)
{
int loopfd = open(loopname, O_RDWR);
if (loopfd == -1) {
return;
}
if (ioctl(loopfd, LOOP_CLR_FD, 0)) {
}
close(loopfd);
}
static long syz_mount_image(
volatile long fsarg,
volatile long dir,
volatile long flags,
volatile long optsarg,
volatile long change_dir,
volatile unsigned long size,
volatile long image)
{
unsigned char* data = (unsigned char*)image;
int res = -1, err = 0, need_loop_device = !!size;
char* mount_opts = (char*)optsarg;
char* target = (char*)dir;
char* fs = (char*)fsarg;
char* source = NULL;
char loopname[64];
if (need_loop_device) {
int loopfd;
memset(loopname, 0, sizeof(loopname));
snprintf(loopname, sizeof(loopname), "/dev/loop%llu", procid);
if (setup_loop_device(data, size, loopname, &loopfd) == -1)
return -1;
close(loopfd);
source = loopname;
}
mkdir(target, 0777);
char opts[256];
memset(opts, 0, sizeof(opts));
if (strlen(mount_opts) > (sizeof(opts) - 32)) {
}
strncpy(opts, mount_opts, sizeof(opts) - 32);
if (strcmp(fs, "iso9660") == 0) {
flags |= MS_RDONLY;
} else if (strncmp(fs, "ext", 3) == 0) {
bool has_remount_ro = false;
char* remount_ro_start = strstr(opts, "errors=remount-ro");
if (remount_ro_start != NULL) {
char after = *(remount_ro_start + strlen("errors=remount-ro"));
char before = remount_ro_start == opts ? '\0' : *(remount_ro_start - 1);
has_remount_ro = ((before == '\0' || before == ',') && (after == '\0' || after == ','));
}
if (strstr(opts, "errors=panic") || !has_remount_ro)
strcat(opts, ",errors=continue");
} else if (strcmp(fs, "xfs") == 0) {
strcat(opts, ",nouuid");
} else if (strncmp(fs, "gfs2", 4) == 0 && (strstr(opts, "errors=panic") || strstr(opts, "debug"))) {
strcat(opts, ",errors=withdraw");
}
res = mount(source, target, fs, flags, opts);
if (res == -1) {
err = errno;
goto error_clear_loop;
}
res = open(target, O_RDONLY | O_DIRECTORY);
if (res == -1) {
err = errno;
goto error_clear_loop;
}
if (change_dir) {
res = chdir(target);
if (res == -1) {
err = errno;
}
}
error_clear_loop:
if (need_loop_device)
reset_loop_device(loopname);
errno = err;
return res;
}
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;
if (write(1, "executing program\n", sizeof("executing program\n") - 1)) {}
// syz_mount_image$ntfs3 arguments: [
// fs: ptr[in, buffer] {
// buffer: {6e 74 66 73 33 00} (length 0x6)
// }
// dir: ptr[in, buffer] {
// buffer: {2e 2f 66 69 6c 65 30 00} (length 0x8)
// }
// flags: mount_flags = 0x0 (8 bytes)
// opts: ptr[in, fs_options[ntfs3_options]] {
// fs_options[ntfs3_options] {
// elems: array[fs_opt_elem[ntfs3_options]] {
// fs_opt_elem[ntfs3_options] {
// elem: union ntfs3_options {
// sparse: buffer: {73 70 61 72 73 65} (length 0x6)
// }
// comma: const = 0x2c (1 bytes)
// }
// fs_opt_elem[ntfs3_options] {
// elem: union ntfs3_options {
// hide_dot_files: buffer: {68 69 64 65 5f 64 6f 74 5f 66 69 6c 65 73} (length 0xe)
// }
// comma: const = 0x2c (1 bytes)
// }
// }
// common: array[fs_opt_elem[fs_options_common]] {
// }
// null: const = 0x0 (1 bytes)
// }
// }
// chdir: int8 = 0x1 (1 bytes)
// size: len = 0x1f34d (8 bytes)
// img: ptr[in, buffer] {
// buffer: (compressed buffer with length 0x1f34d)
// }
// ]
// returns fd_dir
memcpy((void*)0x20000001f340, "ntfs3\000", 6);
memcpy((void*)0x20000001f380, "./file0\000", 8);
memcpy((void*)0x200000000040, "sparse", 6);
*(uint8_t*)0x200000000046 = 0x2c;
memcpy((void*)0x200000000047, "hide_dot_files", 14);
*(uint8_t*)0x200000000055 = 0x2c;
*(uint8_t*)0x200000000056 = 0;
memcpy((void*)0x20000003e740, "... [truncated large byte array] ...", 127821);
syz_mount_image(/*fs=*/0x20000001f340, /*dir=*/0x20000001f380, /*flags=*/0, /*opts=*/0x200000000040, /*chdir=*/1, /*size=*/0x1f34d, /*img=*/0x20000003e740);
return 0;
}
]
|
| 2/1 |
2026/05/17 00:45 |
action |
kernel-checkouter |
1m
Results: map[KernelSrc:/app/workdir/cache/src/ae13d14ba43c9fbd1af73b1b694531ed5ba46e0b]
|
| 3/1 |
2026/05/17 00:46 |
action |
kernel-builder |
27m
Results: map[KernelObj:/app/workdir/cache/build/ddb7d69c570ab662bec8ad4c7ae4481b61d75a59]
|
| 4/1 |
2026/05/17 01:14 |
action |
codesearch-prepare |
16m
Results: map[Index:codesearch-index]
|
| 5/1 |
2026/05/17 01:30 |
agent |
expert |
3m
Model:
Results: map[DenialOfService:false Exploitable:false FilesystemTrigger:true NetworkTrigger:false PeripheralTrigger:true RemoteTrigger:false Unprivileged:false 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:
loop0: detected capacity change from 0 to 4096
ntfs3(loop0): Different NTFS sector size (2048) and media sector size (512).
=====================================================
BUG: KMSAN: uninit-value in ntfs_iomap_begin+0x8c0/0x1460 fs/ntfs3/inode.c:825
ntfs_iomap_begin+0x8c0/0x1460 fs/ntfs3/inode.c:825
iomap_iter+0x9b7/0x1540 fs/iomap/iter.c:110
iomap_read_folio+0x262/0x750 fs/iomap/buffered-io.c:587
ntfs_read_folio+0x74a/0x770 fs/ntfs3/inode.c:697
filemap_read_folio mm/filemap.c:2496 [inline]
do_read_cache_folio+0x993/0x1470 mm/filemap.c:4096
do_read_cache_page mm/filemap.c:4162 [inline]
read_cache_page+0x63/0x1e0 mm/filemap.c:4171
read_mapping_page include/linux/pagemap.h:1022 [inline]
inode_read_data+0xb3/0x6b0 fs/ntfs3/inode.c:1116
ntfs_fill_super+0x6a24/0x7e50 fs/ntfs3/super.c:1549
get_tree_bdev_flags+0x6e6/0x920 fs/super.c:1694
get_tree_bdev+0x38/0x50 fs/super.c:1717
ntfs_fs_get_tree+0x35/0x40 fs/ntfs3/super.c:1788
vfs_get_tree+0xb3/0x5d0 fs/super.c:1754
fc_mount fs/namespace.c:1193 [inline]
do_new_mount_fc fs/namespace.c:3760 [inline]
do_new_mount+0x885/0x1dd0 fs/namespace.c:3836
path_mount+0x7a2/0x20b0 fs/namespace.c:4146
do_mount fs/namespace.c:4159 [inline]
__do_sys_mount fs/namespace.c:4348 [inline]
__se_sys_mount+0x704/0x7f0 fs/namespace.c:4325
__x64_sys_mount+0xe4/0x150 fs/namespace.c:4325
x64_sys_call+0x39f0/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:166
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Local variable lcn created at:
ntfs_iomap_begin+0x15d/0x1460 fs/ntfs3/inode.c:786
iomap_iter+0x9b7/0x1540 fs/iomap/iter.c:110
CPU: 1 UID: 0 PID: 6051 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
=====================================================
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 <errno.h>
#include <fcntl.h>
#include <setjmp.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
#include <linux/loop.h>
#ifndef __NR_memfd_create
#define __NR_memfd_create 319
#endif
static unsigned long long procid;
//% This code is derived from puff.{c,h}, found in the zlib development. The
//% original files come with the following copyright notice:
//% Copyright (C) 2002-2013 Mark Adler, all rights reserved
//% version 2.3, 21 Jan 2013
//% This software is provided 'as-is', without any express or implied
//% warranty. In no event will the author be held liable for any damages
//% arising from the use of this software.
//% Permission is granted to anyone to use this software for any purpose,
//% including commercial applications, and to alter it and redistribute it
//% freely, subject to the following restrictions:
//% 1. The origin of this software must not be misrepresented; you must not
//% claim that you wrote the original software. If you use this software
//% in a product, an acknowledgment in the product documentation would be
//% appreciated but is not required.
//% 2. Altered source versions must be plainly marked as such, and must not be
//% misrepresented as being the original software.
//% 3. This notice may not be removed or altered from any source distribution.
//% Mark Adler madler@alumni.caltech.edu
//% BEGIN CODE DERIVED FROM puff.{c,h}
#define MAXBITS 15
#define MAXLCODES 286
#define MAXDCODES 30
#define MAXCODES (MAXLCODES + MAXDCODES)
#define FIXLCODES 288
struct puff_state {
unsigned char* out;
unsigned long outlen;
unsigned long outcnt;
const unsigned char* in;
unsigned long inlen;
unsigned long incnt;
int bitbuf;
int bitcnt;
jmp_buf env;
};
static int puff_bits(struct puff_state* s, int need)
{
long val = s->bitbuf;
while (s->bitcnt < need) {
if (s->incnt == s->inlen)
longjmp(s->env, 1);
val |= (long)(s->in[s->incnt++]) << s->bitcnt;
s->bitcnt += 8;
}
s->bitbuf = (int)(val >> need);
s->bitcnt -= need;
return (int)(val & ((1L << need) - 1));
}
static int puff_stored(struct puff_state* s)
{
s->bitbuf = 0;
s->bitcnt = 0;
if (s->incnt + 4 > s->inlen)
return 2;
unsigned len = s->in[s->incnt++];
len |= s->in[s->incnt++] << 8;
if (s->in[s->incnt++] != (~len & 0xff) ||
s->in[s->incnt++] != ((~len >> 8) & 0xff))
return -2;
if (s->incnt + len > s->inlen)
return 2;
if (s->outcnt + len > s->outlen)
return 1;
for (; len--; s->outcnt++, s->incnt++) {
if (s->in[s->incnt])
s->out[s->outcnt] = s->in[s->incnt];
}
return 0;
}
struct puff_huffman {
short* count;
short* symbol;
};
static int puff_decode(struct puff_state* s, const struct puff_huffman* h)
{
int first = 0;
int index = 0;
int bitbuf = s->bitbuf;
int left = s->bitcnt;
int code = first = index = 0;
int len = 1;
short* next = h->count + 1;
while (1) {
while (left--) {
code |= bitbuf & 1;
bitbuf >>= 1;
int count = *next++;
if (code - count < first) {
s->bitbuf = bitbuf;
s->bitcnt = (s->bitcnt - len) & 7;
return h->symbol[index + (code - first)];
}
index += count;
first += count;
first <<= 1;
code <<= 1;
len++;
}
left = (MAXBITS + 1) - len;
if (left == 0)
break;
if (s->incnt == s->inlen)
longjmp(s->env, 1);
bitbuf = s->in[s->incnt++];
if (left > 8)
left = 8;
}
return -10;
}
static int puff_construct(struct puff_huffman* h, const short* length, int n)
{
int len;
for (len = 0; len <= MAXBITS; len++)
h->count[len] = 0;
int symbol;
for (symbol = 0; symbol < n; symbol++)
(h->count[length[symbol]])++;
if (h->count[0] == n)
return 0;
int left = 1;
for (len = 1; len <= MAXBITS; len++) {
left <<= 1;
left -= h->count[len];
if (left < 0)
return left;
}
short offs[MAXBITS + 1];
offs[1] = 0;
for (len = 1; len < MAXBITS; len++)
offs[len + 1] = offs[len] + h->count[len];
for (symbol = 0; symbol < n; symbol++)
if (length[symbol] != 0)
h->symbol[offs[length[symbol]]++] = symbol;
return left;
}
static int puff_codes(struct puff_state* s,
const struct puff_huffman* lencode,
const struct puff_huffman* distcode)
{
static const short lens[29] = {
3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258};
static const short lext[29] = {
0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0};
static const short dists[30] = {
1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
8193, 12289, 16385, 24577};
static const short dext[30] = {
0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
12, 12, 13, 13};
int symbol;
do {
symbol = puff_decode(s, lencode);
if (symbol < 0)
return symbol;
if (symbol < 256) {
if (s->outcnt == s->outlen)
return 1;
if (symbol)
s->out[s->outcnt] = symbol;
s->outcnt++;
} else if (symbol > 256) {
symbol -= 257;
if (symbol >= 29)
return -10;
int len = lens[symbol] + puff_bits(s, lext[symbol]);
symbol = puff_decode(s, distcode);
if (symbol < 0)
return symbol;
unsigned dist = dists[symbol] + puff_bits(s, dext[symbol]);
if (dist > s->outcnt)
return -11;
if (s->outcnt + len > s->outlen)
return 1;
while (len--) {
if (dist <= s->outcnt && s->out[s->outcnt - dist])
s->out[s->outcnt] = s->out[s->outcnt - dist];
s->outcnt++;
}
}
} while (symbol != 256);
return 0;
}
static int puff_fixed(struct puff_state* s)
{
static int virgin = 1;
static short lencnt[MAXBITS + 1], lensym[FIXLCODES];
static short distcnt[MAXBITS + 1], distsym[MAXDCODES];
static struct puff_huffman lencode, distcode;
if (virgin) {
lencode.count = lencnt;
lencode.symbol = lensym;
distcode.count = distcnt;
distcode.symbol = distsym;
short lengths[FIXLCODES];
int symbol;
for (symbol = 0; symbol < 144; symbol++)
lengths[symbol] = 8;
for (; symbol < 256; symbol++)
lengths[symbol] = 9;
for (; symbol < 280; symbol++)
lengths[symbol] = 7;
for (; symbol < FIXLCODES; symbol++)
lengths[symbol] = 8;
puff_construct(&lencode, lengths, FIXLCODES);
for (symbol = 0; symbol < MAXDCODES; symbol++)
lengths[symbol] = 5;
puff_construct(&distcode, lengths, MAXDCODES);
virgin = 0;
}
return puff_codes(s, &lencode, &distcode);
}
static int puff_dynamic(struct puff_state* s)
{
static const short order[19] =
{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
int nlen = puff_bits(s, 5) + 257;
int ndist = puff_bits(s, 5) + 1;
int ncode = puff_bits(s, 4) + 4;
if (nlen > MAXLCODES || ndist > MAXDCODES)
return -3;
short lengths[MAXCODES];
int index;
for (index = 0; index < ncode; index++)
lengths[order[index]] = puff_bits(s, 3);
for (; index < 19; index++)
lengths[order[index]] = 0;
short lencnt[MAXBITS + 1], lensym[MAXLCODES];
struct puff_huffman lencode = {lencnt, lensym};
int err = puff_construct(&lencode, lengths, 19);
if (err != 0)
return -4;
index = 0;
while (index < nlen + ndist) {
int symbol;
int len;
symbol = puff_decode(s, &lencode);
if (symbol < 0)
return symbol;
if (symbol < 16)
lengths[index++] = symbol;
else {
len = 0;
if (symbol == 16) {
if (index == 0)
return -5;
len = lengths[index - 1];
symbol = 3 + puff_bits(s, 2);
} else if (symbol == 17)
symbol = 3 + puff_bits(s, 3);
else
symbol = 11 + puff_bits(s, 7);
if (index + symbol > nlen + ndist)
return -6;
while (symbol--)
lengths[index++] = len;
}
}
if (lengths[256] == 0)
return -9;
err = puff_construct(&lencode, lengths, nlen);
if (err && (err < 0 || nlen != lencode.count[0] + lencode.count[1]))
return -7;
short distcnt[MAXBITS + 1], distsym[MAXDCODES];
struct puff_huffman distcode = {distcnt, distsym};
err = puff_construct(&distcode, lengths + nlen, ndist);
if (err && (err < 0 || ndist != distcode.count[0] + distcode.count[1]))
return -8;
return puff_codes(s, &lencode, &distcode);
}
static int puff(
unsigned char* dest,
unsigned long* destlen,
const unsigned char* source,
unsigned long sourcelen)
{
struct puff_state s = {
.out = dest,
.outlen = *destlen,
.outcnt = 0,
.in = source,
.inlen = sourcelen,
.incnt = 0,
.bitbuf = 0,
.bitcnt = 0,
};
int err;
if (setjmp(s.env) != 0)
err = 2;
else {
int last;
do {
last = puff_bits(&s, 1);
int type = puff_bits(&s, 2);
err = type == 0 ? puff_stored(&s) : (type == 1 ? puff_fixed(&s) : (type == 2 ? puff_dynamic(&s) : -1));
if (err != 0)
break;
} while (!last);
}
*destlen = s.outcnt;
return err;
}
//% END CODE DERIVED FROM puff.{c,h}
#define ZLIB_HEADER_WIDTH 2
static int puff_zlib_to_file(const unsigned char* source, unsigned long sourcelen, int dest_fd)
{
if (sourcelen < ZLIB_HEADER_WIDTH)
return 0;
source += ZLIB_HEADER_WIDTH;
sourcelen -= ZLIB_HEADER_WIDTH;
const unsigned long max_destlen = 132 << 20;
void* ret = mmap(0, max_destlen, PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0);
if (ret == MAP_FAILED)
return -1;
unsigned char* dest = (unsigned char*)ret;
unsigned long destlen = max_destlen;
int err = puff(dest, &destlen, source, sourcelen);
if (err) {
munmap(dest, max_destlen);
errno = -err;
return -1;
}
if (write(dest_fd, dest, destlen) != (ssize_t)destlen) {
munmap(dest, max_destlen);
return -1;
}
return munmap(dest, max_destlen);
}
static int setup_loop_device(unsigned char* data, unsigned long size, const char* loopname, int* loopfd_p)
{
int err = 0, loopfd = -1;
int memfd = syscall(__NR_memfd_create, "syzkaller", 0);
if (memfd == -1) {
err = errno;
goto error;
}
if (puff_zlib_to_file(data, size, memfd)) {
err = errno;
goto error_close_memfd;
}
loopfd = open(loopname, O_RDWR);
if (loopfd == -1) {
err = errno;
goto error_close_memfd;
}
if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
if (errno != EBUSY) {
err = errno;
goto error_close_loop;
}
ioctl(loopfd, LOOP_CLR_FD, 0);
usleep(1000);
if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
err = errno;
goto error_close_loop;
}
}
close(memfd);
*loopfd_p = loopfd;
return 0;
error_close_loop:
close(loopfd);
error_close_memfd:
close(memfd);
error:
errno = err;
return -1;
}
static void reset_loop_device(const char* loopname)
{
int loopfd = open(loopname, O_RDWR);
if (loopfd == -1) {
return;
}
if (ioctl(loopfd, LOOP_CLR_FD, 0)) {
}
close(loopfd);
}
static long syz_mount_image(
volatile long fsarg,
volatile long dir,
volatile long flags,
volatile long optsarg,
volatile long change_dir,
volatile unsigned long size,
volatile long image)
{
unsigned char* data = (unsigned char*)image;
int res = -1, err = 0, need_loop_device = !!size;
char* mount_opts = (char*)optsarg;
char* target = (char*)dir;
char* fs = (char*)fsarg;
char* source = NULL;
char loopname[64];
if (need_loop_device) {
int loopfd;
memset(loopname, 0, sizeof(loopname));
snprintf(loopname, sizeof(loopname), "/dev/loop%llu", procid);
if (setup_loop_device(data, size, loopname, &loopfd) == -1)
return -1;
close(loopfd);
source = loopname;
}
mkdir(target, 0777);
char opts[256];
memset(opts, 0, sizeof(opts));
if (strlen(mount_opts) > (sizeof(opts) - 32)) {
}
strncpy(opts, mount_opts, sizeof(opts) - 32);
if (strcmp(fs, "iso9660") == 0) {
flags |= MS_RDONLY;
} else if (strncmp(fs, "ext", 3) == 0) {
bool has_remount_ro = false;
char* remount_ro_start = strstr(opts, "errors=remount-ro");
if (remount_ro_start != NULL) {
char after = *(remount_ro_start + strlen("errors=remount-ro"));
char before = remount_ro_start == opts ? '\0' : *(remount_ro_start - 1);
has_remount_ro = ((before == '\0' || before == ',') && (after == '\0' || after == ','));
}
if (strstr(opts, "errors=panic") || !has_remount_ro)
strcat(opts, ",errors=continue");
} else if (strcmp(fs, "xfs") == 0) {
strcat(opts, ",nouuid");
} else if (strncmp(fs, "gfs2", 4) == 0 && (strstr(opts, "errors=panic") || strstr(opts, "debug"))) {
strcat(opts, ",errors=withdraw");
}
res = mount(source, target, fs, flags, opts);
if (res == -1) {
err = errno;
goto error_clear_loop;
}
res = open(target, O_RDONLY | O_DIRECTORY);
if (res == -1) {
err = errno;
goto error_clear_loop;
}
if (change_dir) {
res = chdir(target);
if (res == -1) {
err = errno;
}
}
error_clear_loop:
if (need_loop_device)
reset_loop_device(loopname);
errno = err;
return res;
}
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;
if (write(1, "executing program\n", sizeof("executing program\n") - 1)) {}
// syz_mount_image$ntfs3 arguments: [
// fs: ptr[in, buffer] {
// buffer: {6e 74 66 73 33 00} (length 0x6)
// }
// dir: ptr[in, buffer] {
// buffer: {2e 2f 66 69 6c 65 30 00} (length 0x8)
// }
// flags: mount_flags = 0x0 (8 bytes)
// opts: ptr[in, fs_options[ntfs3_options]] {
// fs_options[ntfs3_options] {
// elems: array[fs_opt_elem[ntfs3_options]] {
// fs_opt_elem[ntfs3_options] {
// elem: union ntfs3_options {
// sparse: buffer: {73 70 61 72 73 65} (length 0x6)
// }
// comma: const = 0x2c (1 bytes)
// }
// fs_opt_elem[ntfs3_options] {
// elem: union ntfs3_options {
// hide_dot_files: buffer: {68 69 64 65 5f 64 6f 74 5f 66 69 6c 65 73} (length 0xe)
// }
// comma: const = 0x2c (1 bytes)
// }
// }
// common: array[fs_opt_elem[fs_options_common]] {
// }
// null: const = 0x0 (1 bytes)
// }
// }
// chdir: int8 = 0x1 (1 bytes)
// size: len = 0x1f34d (8 bytes)
// img: ptr[in, buffer] {
// buffer: (compressed buffer with length 0x1f34d)
// }
// ]
// returns fd_dir
memcpy((void*)0x20000001f340, "ntfs3\000", 6);
memcpy((void*)0x20000001f380, "./file0\000", 8);
memcpy((void*)0x200000000040, "sparse", 6);
*(uint8_t*)0x200000000046 = 0x2c;
memcpy((void*)0x200000000047, "hide_dot_files", 14);
*(uint8_t*)0x200000000055 = 0x2c;
*(uint8_t*)0x200000000056 = 0;
memcpy((void*)0x20000003e740, "... [truncated large byte array] ...", 127821);
syz_mount_image(/*fs=*/0x20000001f340, /*dir=*/0x20000001f380, /*flags=*/0, /*opts=*/0x200000000040, /*chdir=*/1, /*size=*/0x1f34d, /*img=*/0x20000003e740);
return 0;
}
Reply: Based on the analysis of the source code and the KMSAN report, here is the assessment of the bug:
**Root Cause Analysis:**
The bug is a KMSAN uninitialized value report in `ntfs_iomap_begin`.
The uninitialized value is the local variable `lcn`, which is passed by reference to `attr_data_get_block()`.
Inside `attr_data_get_block()`, if the requested virtual cluster number (`vcn`) is not found in the run list (`run_lookup_entry` returns false) and the caller did not request allocation of new clusters (`new == NULL`), the function sets `*len = 0` and jumps to the `ok` label, returning `0` (success) without ever initializing `*lcn`.
Back in `ntfs_iomap_begin()`, the uninitialized `lcn` is then used in a series of comparisons:
```c
if (lcn == EOF_LCN) { ... }
...
if (lcn == RESIDENT_LCN) {
if (offset >= clen) { ... return -EFAULT; }
...
}
if (!clen) {
return -EINVAL;
}
```
**Security Impact:**
Although `lcn` is uninitialized, the variable `clen` (which corresponds to `*len` set by `attr_data_get_block`) is guaranteed to be `0` in this specific code path.
Because `clen` is `0`, the function will always end up returning an error:
- If `lcn` happens to match `RESIDENT_LCN`, it checks `offset >= clen`. Since `offset` is a file offset (always `>= 0`) and `clen` is `0`, this condition is always true, and the function returns `-EFAULT`.
- If `lcn` is anything else (or if it was `EOF_LCN` and got reassigned to `SPARSE_LCN`), the code eventually reaches `if (!clen)`, which evaluates to true, and returns `-EINVAL`.
In all cases, the uninitialized value does not influence the control flow in any dangerous way. It is not used for memory accesses, pointer arithmetic, or leaked to userspace. It simply results in a read error (`-EINVAL` or `-EFAULT`), which gracefully propagates up the call stack and fails the operation (e.g., failing the mount process).
Therefore, this is a **benign** uninitialized value use. It is **not exploitable** and does **not cause a Denial of Service** (the kernel does not crash or hang; it just rejects the corrupted filesystem).
**Reachability:**
The bug can be triggered by mounting a maliciously crafted NTFS filesystem image where the run list does not cover the allocated size of a file.
However, the `ntfs3` filesystem does not have the `FS_USERNS_MOUNT` flag set in its `file_system_type` definition. This means it cannot be mounted from within a user namespace. Mounting it requires `CAP_SYS_ADMIN` in the initial user namespace.
Thus, the bug is **not accessible from unprivileged processes** or **user namespaces**. It can only be triggered if the root user explicitly mounts the image, or if the system is configured to auto-mount external media (e.g., USB drives on a Desktop environment), making it a **Peripheral / Malicious Filesystem Trigger**.
|
| 6/2 |
2026/05/17 01:30 |
llm |
expert |
0m
Model:
Tokens:
input: 12100
output: 46
thoughts: 772
Thoughts: **KMSAN Report Deep Dive: Uninitialized Value in NTFS3**
Okay, I'm looking at this KMSAN report and it immediately jumps out at me: an uninitialized value in `ntfs_iomap_begin`. The stack trace gives me a clear path to the issue, starting with `ntfs_iomap_begin` in `fs/ntfs3/inode.c`, all the way up to the mount call. The specific line highlighted is `BUG: KMSAN: uninit-value in ntfs_iomap_begin+0x8c0/0x1460 fs/ntfs3/inode.c:825`.
The error originates in `ntfs_iomap_begin`, and the uninitialized value, `lcn`, is created at `ntfs_iomap_begin+0x15d/0x1460 fs/ntfs3/inode.c:786`.
Given that I'm seeing this with NTFS3, it is likely the root cause is in how the logical cluster number is handled during I/O operations. This will be the first place to look. I need to understand how `lcn` is being calculated or read from the NTFS metadata and under what conditions it is not properly initialized.
|
| 7/2 |
2026/05/17 01:30 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:fs/ntfs3/inode.c IncludeLines:true Name:ntfs_iomap_begin]
Results: map[SourceCode: 761: /*
762: * Function to get mapping vbo -> lbo.
763: * used with:
764: * - iomap_zero_range
765: * - iomap_truncate_page
766: * - iomap_dio_rw
767: * - iomap_file_buffered_write
768: * - iomap_bmap
769: * - iomap_fiemap
770: * - iomap_bio_read_folio
771: * - iomap_bio_readahead
772: */
773: static int ntfs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
774: unsigned int flags, struct iomap *iomap,
775: struct iomap *srcmap)
776: {
777: struct ntfs_inode *ni = ntfs_i(inode);
778: struct ntfs_sb_info *sbi = ni->mi.sbi;
779: u8 cluster_bits = sbi->cluster_bits;
780: CLST vcn = offset >> cluster_bits;
781: u32 off = offset & sbi->cluster_mask;
782: bool rw = flags & IOMAP_WRITE;
783: loff_t endbyte = offset + length;
784: void *res = NULL;
785: int err;
786: CLST lcn, clen, clen_max = 1;
787: bool new_clst = false;
788: bool no_da;
789: bool zero = false;
790: if (unlikely(ntfs3_forced_shutdown(sbi->sb)))
791: return -EIO;
792:
793: if (flags & IOMAP_REPORT) {
794: if (offset > ntfs_get_maxbytes(ni)) {
795: /* called from fiemap/bmap. */
796: return -EINVAL;
797: }
798:
799: if (offset >= inode->i_size) {
800: /* special code for report. */
801: return -ENOENT;
802: }
803: }
804:
805: if (IOMAP_ZERO == flags && (endbyte & sbi->cluster_mask)) {
806: rw = true;
807: } else if (rw) {
808: clen_max = bytes_to_cluster(sbi, endbyte) - vcn;
809: }
810:
811: /*
812: * Force to allocate clusters if directIO(write) or writeback_range.
813: * NOTE: attr_data_get_block allocates clusters only for sparse file.
814: * Normal file allocates clusters in attr_set_size.
815: */
816: no_da = flags == (IOMAP_DIRECT | IOMAP_WRITE) || srcmap == WB_NO_DA;
817:
818: err = attr_data_get_block(ni, vcn, clen_max, &lcn, &clen,
819: rw ? &new_clst : NULL, zero, &res, no_da);
820:
821: if (err) {
822: return err;
823: }
824:
825: if (lcn == EOF_LCN) {
826: /* request out of file. */
827: if (flags & IOMAP_REPORT) {
828: /* special code for report. */
829: return -ENOENT;
830: }
831:
832: if (rw) {
833: /* should never be here. */
834: return -EINVAL;
835: }
836: lcn = SPARSE_LCN;
837: }
838:
839: iomap->flags = new_clst ? IOMAP_F_NEW : 0;
840:
841: if (lcn == RESIDENT_LCN) {
842: if (offset >= clen) {
843: kfree(res);
844: if (flags & IOMAP_REPORT) {
845: /* special code for report. */
846: return -ENOENT;
847: }
848: return -EFAULT;
849: }
850:
851: iomap->private = iomap->inline_data = res;
852: iomap->type = IOMAP_INLINE;
853: iomap->offset = 0;
854: iomap->length = clen; /* resident size in bytes. */
855: return 0;
856: }
857:
858: if (!clen) {
859: /* broken file? */
860: return -EINVAL;
861: }
862:
863: iomap->bdev = inode->i_sb->s_bdev;
864: iomap->offset = offset;
865: iomap->length = ((loff_t)clen << cluster_bits) - off;
866:
867: if (lcn == COMPRESSED_LCN) {
868: /* should never be here. */
869: return -EOPNOTSUPP;
870: }
871:
872: if (lcn == DELALLOC_LCN) {
873: iomap->type = IOMAP_DELALLOC;
874: iomap->addr = IOMAP_NULL_ADDR;
875: } else {
876:
877: /* Translate clusters into bytes. */
878: iomap->addr = ((loff_t)lcn << cluster_bits) + off;
879: if (length && iomap->length > length)
880: iomap->length = length;
881: else
882: endbyte = offset + iomap->length;
883:
884: if (lcn == SPARSE_LCN) {
885: iomap->addr = IOMAP_NULL_ADDR;
886: iomap->type = IOMAP_HOLE;
887: // if (IOMAP_ZERO == flags && !off) {
888: // iomap->length = (endbyte - offset) &
889: // sbi->cluster_mask_inv;
890: // }
891: } else if (endbyte <= ni->i_valid) {
892: iomap->type = IOMAP_MAPPED;
893: } else if (offset < ni->i_valid) {
894: iomap->type = IOMAP_MAPPED;
895: if (flags & IOMAP_REPORT)
896: iomap->length = ni->i_valid - offset;
897: } else if (rw || (flags & IOMAP_ZERO)) {
898: iomap->type = IOMAP_MAPPED;
899: } else {
900: iomap->type = IOMAP_UNWRITTEN;
901: }
902: }
903:
904: if ((flags & IOMAP_ZERO) &&
905: (iomap->type == IOMAP_MAPPED || iomap->type == IOMAP_DELALLOC)) {
906: /* Avoid too large requests. */
907: u32 tail;
908: u32 off_a = offset & (PAGE_SIZE - 1);
909: if (off_a)
910: tail = PAGE_SIZE - off_a;
911: else
912: tail = PAGE_SIZE;
913:
914: if (iomap->length > tail)
915: iomap->length = tail;
916: }
917:
918: return 0;
919: }
SourceFile:fs/ntfs3/inode.c]
|
| 8/2 |
2026/05/17 01:30 |
llm |
expert |
0m
Model:
Tokens:
input: 15625
output: 45
thoughts: 184
Thoughts: **Analyzing a Potential Uninitialized Variable in NTFS3**
Okay, so I'm looking at this `ntfs_iomap_begin` function within the NTFS3 filesystem code. I see that the variable `lcn` (logical cluster number) is initialized to `lcn` right here at `ntfs_iomap_begin+0x15d/0x1460 fs/ntfs3/inode.c:786`. Now, the important part seems to be how it's used later, specifically around line 825: `if (lcn == EOF_LCN)`.
My concern is what happens *before* that check. `lcn` gets passed to `attr_data_get_block` at line 818. The critical thing to note is that `attr_data_get_block` can potentially return zero (indicating success, perhaps), *without* actually modifying the value of `lcn` in every instance. That's the crux of the issue, right? An uninitialized `lcn` being used in the comparison at line 825 could be a serious bug. The code isn't explicitly checking for this case, so it's a latent vulnerability. It's time to check `attr_data_get_block` thoroughly, especially the codepaths that lead to a return of 0 *without* the `lcn` parameter being initialized. That's where the problem is almost certainly hiding.
|
| 9/2 |
2026/05/17 01:30 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:fs/ntfs3/inode.c IncludeLines:true Name:attr_data_get_block]
Results: map[SourceCode: 942: /*
943: * attr_data_get_block - Returns 'lcn' and 'len' for given 'vcn'.
944: *
945: * @new == NULL means just to get current mapping for 'vcn'
946: * @new != NULL means allocate real cluster if 'vcn' maps to hole
947: * @zero - zeroout new allocated clusters
948: *
949: * NOTE:
950: * - @new != NULL is called only for sparsed or compressed attributes.
951: * - new allocated clusters are zeroed via blkdev_issue_zeroout.
952: */
953: int attr_data_get_block(struct ntfs_inode *ni, CLST vcn, CLST clen, CLST *lcn,
954: CLST *len, bool *new, bool zero, void **res, bool no_da)
955: {
956: int err;
957:
958: if (new)
959: *new = false;
960: if (res)
961: *res = NULL;
962:
963: /* Try to find in cache. */
964: down_read(&ni->file.run_lock);
965: if (!no_da && run_lookup_entry(&ni->file.run_da, vcn, lcn, len, NULL)) {
966: /* The requested vcn is delay allocated. */
967: *lcn = DELALLOC_LCN;
968: } else if (run_lookup_entry(&ni->file.run, vcn, lcn, len, NULL)) {
969: /* The requested vcn is known in current run. */
970: } else {
971: *len = 0;
972: }
973: up_read(&ni->file.run_lock);
974:
975: if (*len && (*lcn != SPARSE_LCN || !new))
976: return 0; /* Fast normal way without allocation. */
977:
978: /* No cluster in cache or we need to allocate cluster in hole. */
979: ni_lock(ni);
980: down_write(&ni->file.run_lock);
981:
982: err = attr_data_get_block_locked(ni, vcn, clen, lcn, len, new, zero,
983: res, no_da);
984:
985: up_write(&ni->file.run_lock);
986: ni_unlock(ni);
987:
988: return err;
989: }
SourceFile:fs/ntfs3/attrib.c]
|
| 10/2 |
2026/05/17 01:30 |
llm |
expert |
0m
Model:
Tokens:
input: 16974
output: 43
thoughts: 351
Thoughts: **Analyzing the `attr_data_get_block` Function**
Okay, let's break down this `attr_data_get_block` function snippet. My initial thought is to look at the caching mechanism here. I see it's using a read lock (`down_read`) on `ni->file.run_lock`, which is expected for concurrent access. The code first tries to find the Virtual Cluster Number (VCN) in a delay-allocation structure (`ni->file.run_da`) and then in the regular run structure (`ni->file.run`). Makes sense, checks for delay allocation first. The `run_lookup_entry` call is key here. It seems to update `lcn` (Logical Cluster Number) and `len` (length) based on the lookup.
Now, my focus is on line 975. The code returns 0 early if `*len` is non-zero and either `*lcn` isn't `SPARSE_LCN` or `new` is false. This seems like a fast path when we already have a mapping. However, I'm concerned about a potential edge case. What if `run_lookup_entry` *succeeds* β it returns true, meaning it finds something β but, for some reason, doesn't actually set `*lcn`? It could be that it sets `*len` but fails to update `lcn` with a proper LCN, perhaps due to some internal state within `run_lookup_entry`. In this specific scenario the return would be incorrect, as the next check in the logic will return the function early, not checking the other logic.
My immediate next step is to dive into the `run_lookup_entry` implementation and verify what happens in such cases. The code here is the entry point for understanding the behavior of the logic above.
|
| 11/2 |
2026/05/17 01:30 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:fs/ntfs3/attrib.c IncludeLines:true Name:run_lookup_entry]
Results: map[SourceCode: 193: bool run_lookup_entry(const struct runs_tree *run, CLST vcn, CLST *lcn,
194: CLST *len, size_t *index)
195: {
196: size_t idx;
197: CLST gap;
198: struct ntfs_run *r;
199:
200: /* Fail immediately if nrun was not touched yet. */
201: if (!run->runs)
202: return false;
203:
204: if (!run_lookup(run, vcn, &idx))
205: return false;
206:
207: r = run->runs + idx;
208:
209: if (vcn >= r->vcn + r->len)
210: return false;
211:
212: gap = vcn - r->vcn;
213: if (r->len <= gap)
214: return false;
215:
216: *lcn = r->lcn == SPARSE_LCN ? SPARSE_LCN : (r->lcn + gap);
217:
218: if (len)
219: *len = r->len - gap;
220: if (index)
221: *index = idx;
222:
223: return true;
224: }
SourceFile:fs/ntfs3/run.c]
|
| 12/2 |
2026/05/17 01:30 |
llm |
expert |
0m
Model:
Tokens:
input: 18211
output: 47
thoughts: 162
Thoughts: **Analyzing the Conditional Logic in the Code**
Okay, let me break down this conditional logic surrounding `run_lookup_entry`. It's crucial for understanding how this function interacts with the block allocation or retrieval process. My first thought is: I see that `run_lookup_entry` has a side effect: if it returns `true`, then the pointer `*lcn` is *definitely* initialized. Specifically:
```c
*lcn = r->lcn == SPARSE_LCN ? SPARSE_LCN : (r->lcn + gap);
```
This means that if we get a `true` return from `run_lookup_entry`, we *know* the `*lcn` value is valid. The ternary operator here handles the `SPARSE_LCN` case, and the arithmetic `r->lcn + gap` otherwise. This seems to represent setting the Logical Cluster Number, and the setting is conditional.
Conversely, if `run_lookup_entry` returns `false`, the code explicitly sets `*len` to 0:
```c
} else {
*len = 0;
}
```
This is important because it means the function's logic is using `*len = 0` as a signal to mean, "We didn't find anything". Given this, I can infer that if the lookup fails `*len` will equal zero. This makes the following line, the `attr_data_get_block_locked` call, the next logical step. I'll need to look at what `attr_data_get_block_locked` does, but this makes sense as a means of either attempting to allocate a block or returning an existing one if available.
|
| 13/2 |
2026/05/17 01:31 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:fs/ntfs3/attrib.c IncludeLines:true Name:attr_data_get_block_locked]
Results: map[SourceCode: 991: /*
992: * attr_data_get_block_locked - Helper for attr_data_get_block.
993: */
994: int attr_data_get_block_locked(struct ntfs_inode *ni, CLST vcn, CLST clen,
995: CLST *lcn, CLST *len, bool *new, bool zero,
996: void **res, bool no_da)
997: {
998: int err = 0;
999: struct ntfs_sb_info *sbi = ni->mi.sbi;
1000: struct runs_tree *run = &ni->file.run;
1001: struct runs_tree *run_da = &ni->file.run_da;
1002: bool da = sbi->options->delalloc && !no_da;
1003: u8 cluster_bits;
1004: struct ATTRIB *attr, *attr_b;
1005: struct ATTR_LIST_ENTRY *le, *le_b;
1006: struct mft_inode *mi, *mi_b;
1007: CLST hint, svcn, to_alloc, evcn1, next_svcn, asize, end, vcn0;
1008: CLST alloc, evcn;
1009: unsigned fr;
1010: u64 total_size, total_size0;
1011: int step;
1012:
1013: again:
1014: if (da && run_lookup_entry(run_da, vcn, lcn, len, NULL)) {
1015: /* The requested vcn is delay allocated. */
1016: *lcn = DELALLOC_LCN;
1017: } else if (run_lookup_entry(run, vcn, lcn, len, NULL)) {
1018: /* The requested vcn is known in current run. */
1019: } else {
1020: *len = 0;
1021: }
1022:
1023: if (*len) {
1024: if (*lcn != SPARSE_LCN || !new)
1025: goto out; /* normal way without allocation. */
1026: if (clen > *len)
1027: clen = *len;
1028: }
1029:
1030: cluster_bits = sbi->cluster_bits;
1031: step = 0;
1032:
1033: le_b = NULL;
1034: attr_b = ni_find_attr(ni, NULL, &le_b, ATTR_DATA, NULL, 0, NULL, &mi_b);
1035: if (!attr_b) {
1036: err = -ENOENT;
1037: goto out;
1038: }
1039:
1040: if (!attr_b->non_res) {
1041: u32 data_size = le32_to_cpu(attr_b->res.data_size);
1042: *lcn = RESIDENT_LCN;
1043: *len = data_size;
1044: if (res && data_size) {
1045: *res = kmemdup(resident_data(attr_b), data_size,
1046: GFP_KERNEL);
1047: if (!*res)
1048: err = -ENOMEM;
1049: }
1050: goto out;
1051: }
1052:
1053: asize = le64_to_cpu(attr_b->nres.alloc_size) >> cluster_bits;
1054: if (vcn >= asize) {
1055: if (new) {
1056: err = -EINVAL;
1057: } else {
1058: *len = 1;
1059: *lcn = EOF_LCN;
1060: }
1061: goto out;
1062: }
1063:
1064: svcn = le64_to_cpu(attr_b->nres.svcn);
1065: evcn1 = le64_to_cpu(attr_b->nres.evcn) + 1;
1066:
1067: attr = attr_b;
1068: le = le_b;
1069: mi = mi_b;
1070:
1071: if (le_b && (vcn < svcn || evcn1 <= vcn)) {
1072: attr = ni_find_attr(ni, attr_b, &le, ATTR_DATA, NULL, 0, &vcn,
1073: &mi);
1074: if (!attr) {
1075: err = -EINVAL;
1076: goto out;
1077: }
1078: svcn = le64_to_cpu(attr->nres.svcn);
1079: evcn1 = le64_to_cpu(attr->nres.evcn) + 1;
1080: }
1081:
1082: /* Load in cache actual information. */
1083: err = attr_load_runs(attr, ni, run, NULL);
1084: if (err)
1085: goto out;
1086:
1087: /* Check for compressed frame. */
1088: err = attr_is_frame_compressed(ni, attr_b, vcn >> NTFS_LZNT_CUNIT,
1089: &hint, run);
1090: if (err)
1091: goto out;
1092:
1093: if (hint) {
1094: /* if frame is compressed - don't touch it. */
1095: *lcn = COMPRESSED_LCN;
1096: /* length to the end of frame. */
1097: *len = NTFS_LZNT_CLUSTERS - (vcn & (NTFS_LZNT_CLUSTERS - 1));
1098: err = 0;
1099: goto out;
1100: }
1101:
1102: if (!*len) {
1103: if (run_lookup_entry(run, vcn, lcn, len, NULL)) {
1104: if (*lcn != SPARSE_LCN || !new)
1105: goto ok; /* Slow normal way without allocation. */
1106:
1107: if (clen > *len)
1108: clen = *len;
1109: } else if (!new) {
1110: /* Here we may return -ENOENT.
1111: * In any case caller gets zero length. */
1112: goto ok;
1113: }
1114: }
1115:
1116: if (!is_attr_ext(attr_b)) {
1117: /* The code below only for sparsed or compressed attributes. */
1118: err = -EINVAL;
1119: goto out;
1120: }
1121:
1122: vcn0 = vcn;
1123: to_alloc = clen;
1124: fr = (sbi->record_size - le32_to_cpu(mi->mrec->used) + 8) / 3 + 1;
1125: /* Allocate frame aligned clusters.
1126: * ntfs.sys usually uses 16 clusters per frame for sparsed or compressed.
1127: * ntfs3 uses 1 cluster per frame for new created sparsed files. */
1128: if (attr_b->nres.c_unit) {
1129: CLST clst_per_frame = 1u << attr_b->nres.c_unit;
1130: CLST cmask = ~(clst_per_frame - 1);
1131:
1132: /* Get frame aligned vcn and to_alloc. */
1133: vcn = vcn0 & cmask;
1134: to_alloc = ((vcn0 + clen + clst_per_frame - 1) & cmask) - vcn;
1135: if (fr < clst_per_frame)
1136: fr = clst_per_frame;
1137: if (vcn != vcn0)
1138: zero = true;
1139:
1140: /* Check if 'vcn' and 'vcn0' in different attribute segments. */
1141: if (vcn < svcn || evcn1 <= vcn) {
1142: struct ATTRIB *attr2;
1143: /* Load runs for truncated vcn. */
1144: attr2 = ni_find_attr(ni, attr_b, &le_b, ATTR_DATA, NULL,
1145: 0, &vcn, &mi);
1146: if (!attr2) {
1147: err = -EINVAL;
1148: goto out;
1149: }
1150: evcn1 = le64_to_cpu(attr2->nres.evcn) + 1;
1151: err = attr_load_runs(attr2, ni, run, NULL);
1152: if (err)
1153: goto out;
1154: }
1155: da = false; /* no delalloc for compressed file. */
1156: }
1157:
1158: if (vcn + to_alloc > asize)
1159: to_alloc = asize - vcn;
1160:
1161: if (da) {
1162: CLST rlen1, rlen2;
1163: if (!ntfs_check_free_space(sbi, to_alloc, 0, true)) {
1164: err = ni_allocate_da_blocks_locked(ni);
1165: if (err)
1166: goto out;
1167: /* Layout of records may be changed. Start again without 'da'. */
1168: da = false;
1169: goto again;
1170: }
1171:
1172: /* run_add_entry consolidates existed ranges. */
1173: rlen1 = run_len(run_da);
1174: if (!run_add_entry(run_da, vcn, SPARSE_LCN, to_alloc, false)) {
1175: err = -ENOMEM;
1176: goto out;
1177: }
1178: rlen2 = run_len(run_da);
1179:
1180: /* new added delay clusters = rlen2 - rlen1. */
1181: ntfs_add_da(sbi, rlen2 - rlen1);
1182: *len = to_alloc;
1183: *lcn = DELALLOC_LCN;
1184: goto ok;
1185: }
1186:
1187: /* Get the last LCN to allocate from. */
1188: hint = 0;
1189:
1190: if (vcn > evcn1) {
1191: if (!run_add_entry(run, evcn1, SPARSE_LCN, vcn - evcn1,
1192: false)) {
1193: err = -ENOMEM;
1194: goto out;
1195: }
1196: } else if (vcn && !run_lookup_entry(run, vcn - 1, &hint, NULL, NULL)) {
1197: hint = -1;
1198: }
1199:
1200: /* Allocate and zeroout new clusters. */
1201: err = attr_allocate_clusters(sbi, run, run_da, vcn, hint + 1, to_alloc,
1202: NULL,
1203: zero ? ALLOCATE_ZERO : ALLOCATE_ONE_FR,
1204: len, fr, lcn, len);
1205: if (err)
1206: goto out;
1207: *new = true;
1208: step = 1;
1209:
1210: end = vcn + *len;
1211: /* Save 'total_size0' to restore if error. */
1212: total_size0 = le64_to_cpu(attr_b->nres.total_size);
1213: total_size = total_size0 + ((u64)*len << cluster_bits);
1214:
1215: if (vcn != vcn0) {
1216: if (!run_lookup_entry(run, vcn0, lcn, len, NULL)) {
1217: err = -EINVAL;
1218: goto out;
1219: }
1220: if (*lcn == SPARSE_LCN) {
1221: /* Internal error. Should not happened. */
1222: WARN_ON(1);
1223: err = -EINVAL;
1224: goto out;
1225: }
1226: /* Check case when vcn0 + len overlaps new allocated clusters. */
1227: if (vcn0 + *len > end)
1228: *len = end - vcn0;
1229: }
1230:
1231: repack:
1232: err = mi_pack_runs(mi, attr, run, max(end, evcn1) - svcn);
1233: if (err)
1234: goto out;
1235:
1236: attr_b->nres.total_size = cpu_to_le64(total_size);
1237: inode_set_bytes(&ni->vfs_inode, total_size);
1238: ni->ni_flags |= NI_FLAG_UPDATE_PARENT;
1239:
1240: mi_b->dirty = true;
1241: mark_inode_dirty(&ni->vfs_inode);
1242:
1243: /* Stored [vcn : next_svcn) from [vcn : end). */
1244: next_svcn = le64_to_cpu(attr->nres.evcn) + 1;
1245:
1246: if (end <= evcn1) {
1247: if (next_svcn == evcn1) {
1248: /* Normal way. Update attribute and exit. */
1249: goto ok;
1250: }
1251: /* Add new segment [next_svcn : evcn1 - next_svcn). */
1252: if (!ni->attr_list.size) {
1253: err = ni_create_attr_list(ni);
1254: if (err)
1255: goto undo1;
1256: /* Layout of records is changed. */
1257: le_b = NULL;
1258: attr_b = ni_find_attr(ni, NULL, &le_b, ATTR_DATA, NULL,
1259: 0, NULL, &mi_b);
1260: if (!attr_b) {
1261: err = -ENOENT;
1262: goto out;
1263: }
1264:
1265: attr = attr_b;
1266: le = le_b;
1267: mi = mi_b;
1268: goto repack;
1269: }
1270: }
1271:
1272: /*
1273: * The code below may require additional cluster (to extend attribute list)
1274: * and / or one MFT record
1275: * It is too complex to undo operations if -ENOSPC occurs deep inside
1276: * in 'ni_insert_nonresident'.
1277: * Return in advance -ENOSPC here if there are no free cluster and no free MFT.
1278: */
1279: if (!ntfs_check_free_space(sbi, 1, 1, false)) {
1280: /* Undo step 1. */
1281: err = -ENOSPC;
1282: goto undo1;
1283: }
1284:
1285: step = 2;
1286: svcn = evcn1;
1287:
1288: /* Estimate next attribute. */
1289: attr = ni_find_attr(ni, attr, &le, ATTR_DATA, NULL, 0, &svcn, &mi);
1290:
1291: if (!attr) {
1292: /* Insert new attribute segment. */
1293: goto ins_ext;
1294: }
1295:
1296: /* Try to update existed attribute segment. */
1297: alloc = bytes_to_cluster(sbi, le64_to_cpu(attr_b->nres.alloc_size));
1298: evcn = le64_to_cpu(attr->nres.evcn);
1299:
1300: if (end < next_svcn)
1301: end = next_svcn;
1302: while (end > evcn) {
1303: /* Remove segment [svcn : evcn). */
1304: mi_remove_attr(NULL, mi, attr);
1305:
1306: if (!al_remove_le(ni, le)) {
1307: err = -EINVAL;
1308: goto out;
1309: }
1310:
1311: if (evcn + 1 >= alloc) {
1312: /* Last attribute segment. */
1313: evcn1 = evcn + 1;
1314: goto ins_ext;
1315: }
1316:
1317: if (ni_load_mi(ni, le, &mi)) {
1318: attr = NULL;
1319: goto out;
1320: }
1321:
1322: attr = mi_find_attr(ni, mi, NULL, ATTR_DATA, NULL, 0, &le->id);
1323: if (!attr) {
1324: err = -EINVAL;
1325: goto out;
1326: }
1327: svcn = le64_to_cpu(attr->nres.svcn);
1328: evcn = le64_to_cpu(attr->nres.evcn);
1329: }
1330:
1331: if (end < svcn)
1332: end = svcn;
1333:
1334: err = attr_load_runs(attr, ni, run, &end);
1335: if (err)
1336: goto out;
1337:
1338: evcn1 = evcn + 1;
1339: attr->nres.svcn = cpu_to_le64(next_svcn);
1340: err = mi_pack_runs(mi, attr, run, evcn1 - next_svcn);
1341: if (err)
1342: goto out;
1343:
1344: le->vcn = cpu_to_le64(next_svcn);
1345: ni->attr_list.dirty = true;
1346: mi->dirty = true;
1347: next_svcn = le64_to_cpu(attr->nres.evcn) + 1;
1348:
1349: ins_ext:
1350: if (evcn1 > next_svcn) {
1351: err = ni_insert_nonresident(ni, ATTR_DATA, NULL, 0, run,
1352: next_svcn, evcn1 - next_svcn,
1353: attr_b->flags, &attr, &mi, NULL);
1354: if (err)
1355: goto out;
1356: }
1357: ok:
1358: run_truncate_around(run, vcn);
1359: out:
1360: if (err && step > 1) {
1361: /* Too complex to restore. */
1362: _ntfs_bad_inode(&ni->vfs_inode);
1363: }
1364:
1365: return err;
1366:
1367: undo1:
1368: /* Undo step1. */
1369: attr_b->nres.total_size = cpu_to_le64(total_size0);
1370: inode_set_bytes(&ni->vfs_inode, total_size0);
1371:
1372: if (run_deallocate_ex(sbi, run, vcn, *len, NULL, false, run_da) ||
1373: !run_add_entry(run, vcn, SPARSE_LCN, *len, false) ||
1374: mi_pack_runs(mi, attr, run, max(end, evcn1) - svcn)) {
1375: _ntfs_bad_inode(&ni->vfs_inode);
1376: }
1377: goto out;
1378: }
SourceFile:fs/ntfs3/attrib.c]
|
| 14/2 |
2026/05/17 01:31 |
llm |
expert |
0m
Model:
Tokens:
input: 24832
output: 43
thoughts: 4600
Thoughts: **Analysis of Potential Uninitialized Variable in NTFS File System Code**
Okay, so I've been digging into this `attr_data_get_block_locked` function and the way it interacts with `ntfs_iomap_begin`. I'm seeing a potential issue with an uninitialized variable, specifically `lcn`. Here's the deal: under certain conditions, primarily when the requested block's information isn't found in the run list and `run_lookup_entry` fails, `lcn` might not get set. In `ntfs_iomap_begin` this `lcn` is then later used without initialization.
The path is as follows: within `attr_data_get_block_locked`, if the run lookup fails and `!new` is true (which means new is `NULL` and therefore never set), it jumps to `ok` and returns 0. If it jumps to `ok`, the function returns without setting `*lcn`, so the `lcn` variable used in the caller, in `ntfs_iomap_begin`, remains uninitialized.
This uninitialized `lcn` is then passed to `ntfs_iomap_begin`, where it is compared to `EOF_LCN`, `RESIDENT_LCN` and used in various other checks. Crucially, the code *should* catch this uninitialized state. Because the `clen` is also zero, the code correctly returns an error (-EINVAL or -EFAULT) if the checks in `ntfs_iomap_begin` do not match.
Specifically, I've tracked the code flow and it always checks that the read length is valid. So either the code will jump to `EOF_LCN` and set `lcn` to `SPARSE_LCN`, or if it reaches `!clen`, it will jump to an error because the length is 0.
My conclusion is that while there is an uninitialized variable, this is unlikely to be exploitable. This is because the code paths that use the uninitialized value immediately return an error, preventing memory corruption, information leaks, or privilege escalation. This is because in any case, the code either returns an error or returns from the function, thus not using the invalid `lcn`. While KMSAN might flag this, it will just result in a read error on a potentially corrupted filesystem. The file read will return an error code and that's it. This could result in a denial of service, but it is not a vulnerability in the kernel.
|
| 15/2 |
2026/05/17 01:31 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:fs/iomap/iter.c IncludeLines:true Name:iomap_iter]
Results: map[SourceCode: 46: /**
47: * iomap_iter - iterate over a ranges in a file
48: * @iter: iteration structue
49: * @ops: iomap ops provided by the file system
50: *
51: * Iterate over filesystem-provided space mappings for the provided file range.
52: *
53: * This function handles cleanup of resources acquired for iteration when the
54: * filesystem indicates there are no more space mappings, which means that this
55: * function must be called in a loop that continues as long it returns a
56: * positive value. If 0 or a negative value is returned, the caller must not
57: * return to the loop body. Within a loop body, there are two ways to break out
58: * of the loop body: leave @iter.status unchanged, or set it to a negative
59: * errno.
60: */
61: int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops)
62: {
63: bool stale = iter->iomap.flags & IOMAP_F_STALE;
64: ssize_t advanced;
65: u64 olen;
66: int ret;
67:
68: trace_iomap_iter(iter, ops, _RET_IP_);
69:
70: if (!iter->iomap.length)
71: goto begin;
72:
73: /*
74: * Calculate how far the iter was advanced and the original length bytes
75: * for ->iomap_end().
76: */
77: advanced = iter->pos - iter->iter_start_pos;
78: olen = iter->len + advanced;
79:
80: if (ops->iomap_end) {
81: ret = ops->iomap_end(iter->inode, iter->iter_start_pos,
82: iomap_length_trim(iter, iter->iter_start_pos,
83: olen),
84: advanced, iter->flags, &iter->iomap);
85: if (ret < 0 && !advanced)
86: return ret;
87: }
88:
89: /* detect old return semantics where this would advance */
90: if (WARN_ON_ONCE(iter->status > 0))
91: iter->status = -EIO;
92:
93: /*
94: * Use iter->len to determine whether to continue onto the next mapping.
95: * Explicitly terminate on error status or if the current iter has not
96: * advanced at all (i.e. no work was done for some reason) unless the
97: * mapping has been marked stale and needs to be reprocessed.
98: */
99: if (iter->status < 0)
100: ret = iter->status;
101: else if (iter->len == 0 || (!advanced && !stale))
102: ret = 0;
103: else
104: ret = 1;
105: iomap_iter_reset_iomap(iter);
106: if (ret <= 0)
107: return ret;
108:
109: begin:
110: ret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags,
111: &iter->iomap, &iter->srcmap);
112: if (ret < 0)
113: return ret;
114: iomap_iter_done(iter);
115: return 1;
116: }
SourceFile:fs/iomap/iter.c]
|
| 16/2 |
2026/05/17 01:31 |
llm |
expert |
0m
Model:
Tokens:
input: 31095
output: 44
thoughts: 194
Thoughts: **Error Propagation in the NTFS Filesystem Initialization**
Okay, so I'm tracing this error path through the NTFS filesystem code. It seems straightforward: if `ops->iomap_begin` in the `iomap_iter` function encounters an `-EINVAL` or `-EFAULT` error, `iomap_iter` simply passes it right back up the chain. No fancy error handling, just propagation. The culprit is likely `iomap_read_folio`, which hands the error off to `do_read_cache_folio`. Eventually, this error makes its way back to `ntfs_fill_super`. This is key, because `ntfs_fill_super` is responsible for initializing the filesystem, so any error there is a serious problem. Now, the stack trace indicates the error originates in `inode_read_data` which is then passed to `ntfs_fill_super` at line 1549, or thereabouts. I need to take a look at the code around line 1549 in `ntfs_fill_super` to see how it handles the potential error from the `iomap` functions. I expect to see the error check and the subsequent error reporting here.
|
| 17/2 |
2026/05/17 01:31 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:fs/ntfs3/super.c IncludeLines:true Name:ntfs_fill_super]
Results: map[SourceCode:1245: /*
1246: * ntfs_fill_super - Try to mount.
1247: */
1248: static int ntfs_fill_super(struct super_block *sb, struct fs_context *fc)
1249: {
1250: int err;
1251: struct ntfs_sb_info *sbi = sb->s_fs_info;
1252: struct block_device *bdev = sb->s_bdev;
1253: struct ntfs_mount_options *fc_opts;
1254: struct ntfs_mount_options *options = NULL;
1255: struct inode *inode;
1256: struct ntfs_inode *ni;
1257: size_t i, tt, bad_len, bad_frags;
1258: CLST vcn, lcn, len;
1259: struct ATTRIB *attr;
1260: const struct VOLUME_INFO *info;
1261: u32 done, bytes;
1262: struct ATTR_DEF_ENTRY *t;
1263: u16 *shared;
1264: struct MFT_REF ref;
1265: bool ro = sb_rdonly(sb);
1266: struct NTFS_BOOT *boot2 = NULL;
1267:
1268: ref.high = 0;
1269:
1270: sbi->sb = sb;
1271: fc_opts = fc->fs_private;
1272: if (!fc_opts) {
1273: errorf(fc, "missing mount options");
1274: return -EINVAL;
1275: }
1276: options = kmemdup(fc_opts, sizeof(*fc_opts), GFP_KERNEL);
1277: if (!options)
1278: return -ENOMEM;
1279:
1280: if (fc_opts->nls_name) {
1281: options->nls_name = kstrdup(fc_opts->nls_name, GFP_KERNEL);
1282: if (!options->nls_name) {
1283: kfree(options);
1284: return -ENOMEM;
1285: }
1286: }
1287: sbi->options = options;
1288: sb->s_flags |= SB_NODIRATIME;
1289: sb->s_magic = 0x7366746e; // "ntfs"
1290: sb->s_op = &ntfs_sops;
1291: sb->s_export_op = &ntfs_export_ops;
1292: sb->s_time_gran = NTFS_TIME_GRAN; // 100 nsec
1293: sb->s_xattr = ntfs_xattr_handlers;
1294: set_default_d_op(sb, options->nocase ? &ntfs_dentry_ops : NULL);
1295:
1296: options->nls = ntfs_load_nls(options->nls_name);
1297: if (IS_ERR(options->nls)) {
1298: options->nls = NULL;
1299: errorf(fc, "Cannot load nls %s", options->nls_name);
1300: err = -EINVAL;
1301: goto out;
1302: }
1303:
1304: if (bdev_max_discard_sectors(bdev) && bdev_discard_granularity(bdev)) {
1305: sbi->discard_granularity = bdev_discard_granularity(bdev);
1306: sbi->discard_granularity_mask_inv =
1307: ~(u64)(sbi->discard_granularity - 1);
1308: }
1309:
1310: /* Parse boot. */
1311: err = ntfs_init_from_boot(sb, bdev_logical_block_size(bdev),
1312: bdev_nr_bytes(bdev), &boot2);
1313: if (err)
1314: goto out;
1315:
1316: /*
1317: * Load $Volume. This should be done before $LogFile
1318: * 'cause 'sbi->volume.ni' is used in 'ntfs_set_state'.
1319: */
1320: ref.low = cpu_to_le32(MFT_REC_VOL);
1321: ref.seq = cpu_to_le16(MFT_REC_VOL);
1322: inode = ntfs_iget5(sb, &ref, &NAME_VOLUME);
1323: if (IS_ERR(inode)) {
1324: err = PTR_ERR(inode);
1325: ntfs_err(sb, "Failed to load $Volume (%d).", err);
1326: goto out;
1327: }
1328:
1329: ni = ntfs_i(inode);
1330:
1331: /* Load and save label (not necessary). */
1332: attr = ni_find_attr(ni, NULL, NULL, ATTR_LABEL, NULL, 0, NULL, NULL);
1333:
1334: if (!attr) {
1335: /* It is ok if no ATTR_LABEL */
1336: } else if (!attr->non_res && !is_attr_ext(attr)) {
1337: /* $AttrDef allows labels to be up to 128 symbols. */
1338: err = utf16s_to_utf8s(resident_data(attr),
1339: le32_to_cpu(attr->res.data_size) >> 1,
1340: UTF16_LITTLE_ENDIAN, sbi->volume.label,
1341: sizeof(sbi->volume.label));
1342: if (err < 0)
1343: sbi->volume.label[0] = 0;
1344: } else {
1345: /* Should we break mounting here? */
1346: //err = -EINVAL;
1347: //goto put_inode_out;
1348: }
1349:
1350: attr = ni_find_attr(ni, attr, NULL, ATTR_VOL_INFO, NULL, 0, NULL, NULL);
1351: if (!attr || is_attr_ext(attr) ||
1352: !(info = resident_data_ex(attr, SIZEOF_ATTRIBUTE_VOLUME_INFO))) {
1353: ntfs_err(sb, "$Volume is corrupted.");
1354: err = -EINVAL;
1355: goto put_inode_out;
1356: }
1357:
1358: sbi->volume.major_ver = info->major_ver;
1359: sbi->volume.minor_ver = info->minor_ver;
1360: sbi->volume.flags = info->flags;
1361: sbi->volume.ni = ni;
1362: if (info->flags & VOLUME_FLAG_DIRTY) {
1363: sbi->volume.real_dirty = true;
1364: ntfs_info(sb, "It is recommended to use chkdsk.");
1365: }
1366:
1367: /* Load $MFTMirr to estimate recs_mirr. */
1368: ref.low = cpu_to_le32(MFT_REC_MIRR);
1369: ref.seq = cpu_to_le16(MFT_REC_MIRR);
1370: inode = ntfs_iget5(sb, &ref, &NAME_MIRROR);
1371: if (IS_ERR(inode)) {
1372: err = PTR_ERR(inode);
1373: ntfs_err(sb, "Failed to load $MFTMirr (%d).", err);
1374: goto out;
1375: }
1376:
1377: sbi->mft.recs_mirr = ntfs_up_cluster(sbi, inode->i_size) >>
1378: sbi->record_bits;
1379:
1380: iput(inode);
1381:
1382: /* Load LogFile to replay. */
1383: ref.low = cpu_to_le32(MFT_REC_LOG);
1384: ref.seq = cpu_to_le16(MFT_REC_LOG);
1385: inode = ntfs_iget5(sb, &ref, &NAME_LOGFILE);
1386: if (IS_ERR(inode)) {
1387: err = PTR_ERR(inode);
1388: ntfs_err(sb, "Failed to load \x24LogFile (%d).", err);
1389: goto out;
1390: }
1391:
1392: ni = ntfs_i(inode);
1393:
1394: err = ntfs_loadlog_and_replay(ni, sbi);
1395: if (err)
1396: goto put_inode_out;
1397:
1398: iput(inode);
1399:
1400: if ((sbi->flags & NTFS_FLAGS_NEED_REPLAY) && !ro) {
1401: ntfs_warn(sb, "failed to replay log file. Can't mount rw!");
1402: err = -EINVAL;
1403: goto out;
1404: }
1405:
1406: if ((sbi->volume.flags & VOLUME_FLAG_DIRTY) && !ro && !options->force) {
1407: ntfs_warn(sb, "volume is dirty and \"force\" flag is not set!");
1408: err = -EINVAL;
1409: goto out;
1410: }
1411:
1412: /* Load $MFT. */
1413: ref.low = cpu_to_le32(MFT_REC_MFT);
1414: ref.seq = cpu_to_le16(1);
1415:
1416: inode = ntfs_iget5(sb, &ref, &NAME_MFT);
1417: if (IS_ERR(inode)) {
1418: err = PTR_ERR(inode);
1419: ntfs_err(sb, "Failed to load $MFT (%d).", err);
1420: goto out;
1421: }
1422:
1423: ni = ntfs_i(inode);
1424:
1425: sbi->mft.used = ni->i_valid >> sbi->record_bits;
1426: tt = inode->i_size >> sbi->record_bits;
1427: sbi->mft.next_free = MFT_REC_USER;
1428:
1429: err = wnd_init(&sbi->mft.bitmap, sb, tt);
1430: if (err)
1431: goto put_inode_out;
1432:
1433: err = ni_load_all_mi(ni);
1434: if (err) {
1435: ntfs_err(sb, "Failed to load $MFT's subrecords (%d).", err);
1436: goto put_inode_out;
1437: }
1438:
1439: sbi->mft.ni = ni;
1440:
1441: /* Load $Bitmap. */
1442: ref.low = cpu_to_le32(MFT_REC_BITMAP);
1443: ref.seq = cpu_to_le16(MFT_REC_BITMAP);
1444: inode = ntfs_iget5(sb, &ref, &NAME_BITMAP);
1445: if (IS_ERR(inode)) {
1446: err = PTR_ERR(inode);
1447: ntfs_err(sb, "Failed to load $Bitmap (%d).", err);
1448: goto out;
1449: }
1450:
1451: #ifndef CONFIG_NTFS3_64BIT_CLUSTER
1452: if (inode->i_size >> 32) {
1453: err = -EINVAL;
1454: goto put_inode_out;
1455: }
1456: #endif
1457:
1458: /* Check bitmap boundary. */
1459: tt = sbi->used.bitmap.nbits;
1460: if (inode->i_size < ntfs3_bitmap_size(tt)) {
1461: ntfs_err(sb, "$Bitmap is corrupted.");
1462: err = -EINVAL;
1463: goto put_inode_out;
1464: }
1465:
1466: err = wnd_init(&sbi->used.bitmap, sb, tt);
1467: if (err) {
1468: ntfs_err(sb, "Failed to initialize $Bitmap (%d).", err);
1469: goto put_inode_out;
1470: }
1471:
1472: iput(inode);
1473:
1474: /* Compute the MFT zone. */
1475: err = ntfs_refresh_zone(sbi);
1476: if (err) {
1477: ntfs_err(sb, "Failed to initialize MFT zone (%d).", err);
1478: goto out;
1479: }
1480:
1481: /* Load $BadClus. */
1482: ref.low = cpu_to_le32(MFT_REC_BADCLUST);
1483: ref.seq = cpu_to_le16(MFT_REC_BADCLUST);
1484: inode = ntfs_iget5(sb, &ref, &NAME_BADCLUS);
1485: if (IS_ERR(inode)) {
1486: err = PTR_ERR(inode);
1487: ntfs_err(sb, "Failed to load $BadClus (%d).", err);
1488: goto out;
1489: }
1490:
1491: ni = ntfs_i(inode);
1492: bad_len = bad_frags = 0;
1493: for (i = 0; run_get_entry(&ni->file.run, i, &vcn, &lcn, &len); i++) {
1494: if (lcn == SPARSE_LCN)
1495: continue;
1496:
1497: bad_len += len;
1498: bad_frags += 1;
1499: if (ro)
1500: continue;
1501:
1502: if (wnd_set_used_safe(&sbi->used.bitmap, lcn, len, &tt) || tt) {
1503: /* Bad blocks marked as free in bitmap. */
1504: ntfs_set_state(sbi, NTFS_DIRTY_ERROR);
1505: }
1506: }
1507: if (bad_len) {
1508: /*
1509: * Notice about bad blocks.
1510: * In normal cases these blocks are marked as used in bitmap.
1511: * And we never allocate space in it.
1512: */
1513: ntfs_notice(sb,
1514: "Volume contains %zu bad blocks in %zu fragments.",
1515: bad_len, bad_frags);
1516: }
1517: iput(inode);
1518:
1519: /* Load $AttrDef. */
1520: ref.low = cpu_to_le32(MFT_REC_ATTR);
1521: ref.seq = cpu_to_le16(MFT_REC_ATTR);
1522: inode = ntfs_iget5(sb, &ref, &NAME_ATTRDEF);
1523: if (IS_ERR(inode)) {
1524: err = PTR_ERR(inode);
1525: ntfs_err(sb, "Failed to load $AttrDef (%d)", err);
1526: goto out;
1527: }
1528:
1529: /*
1530: * Typical $AttrDef contains up to 20 entries.
1531: * Check for extremely large/small size.
1532: */
1533: if (inode->i_size < sizeof(struct ATTR_DEF_ENTRY) ||
1534: inode->i_size > 100 * sizeof(struct ATTR_DEF_ENTRY)) {
1535: ntfs_err(sb, "Looks like $AttrDef is corrupted (size=%llu).",
1536: inode->i_size);
1537: err = -EINVAL;
1538: goto put_inode_out;
1539: }
1540:
1541: bytes = inode->i_size;
1542: sbi->def_table = t = kvmalloc(bytes, GFP_KERNEL);
1543: if (!t) {
1544: err = -ENOMEM;
1545: goto put_inode_out;
1546: }
1547:
1548: /* Read the entire file. */
1549: err = inode_read_data(inode, sbi->def_table, bytes);
1550: if (err) {
1551: ntfs_err(sb, "Failed to read $AttrDef (%d).", err);
1552: goto put_inode_out;
1553: }
1554:
1555: if (ATTR_STD != t->type) {
1556: ntfs_err(sb, "$AttrDef is corrupted.");
1557: err = -EINVAL;
1558: goto put_inode_out;
1559: }
1560:
1561: t += 1;
1562: sbi->def_entries = 1;
1563: done = sizeof(struct ATTR_DEF_ENTRY);
1564:
1565: while (done + sizeof(struct ATTR_DEF_ENTRY) <= bytes) {
1566: u32 t32 = le32_to_cpu(t->type);
1567: u64 sz = le64_to_cpu(t->max_sz);
1568:
1569: if ((t32 & 0xF) || le32_to_cpu(t[-1].type) >= t32)
1570: break;
1571:
1572: if (t->type == ATTR_REPARSE)
1573: sbi->reparse.max_size = sz;
1574: else if (t->type == ATTR_EA)
1575: sbi->ea_max_size = sz;
1576:
1577: done += sizeof(struct ATTR_DEF_ENTRY);
1578: t += 1;
1579: sbi->def_entries += 1;
1580: }
1581: iput(inode);
1582:
1583: /* Load $UpCase. */
1584: ref.low = cpu_to_le32(MFT_REC_UPCASE);
1585: ref.seq = cpu_to_le16(MFT_REC_UPCASE);
1586: inode = ntfs_iget5(sb, &ref, &NAME_UPCASE);
1587: if (IS_ERR(inode)) {
1588: err = PTR_ERR(inode);
1589: ntfs_err(sb, "Failed to load $UpCase (%d).", err);
1590: goto out;
1591: }
1592:
1593: if (inode->i_size != 0x10000 * sizeof(short)) {
1594: err = -EINVAL;
1595: ntfs_err(sb, "$UpCase is corrupted.");
1596: goto put_inode_out;
1597: }
1598:
1599: /* Read the entire file. */
1600: err = inode_read_data(inode, sbi->upcase, 0x10000 * sizeof(short));
1601: if (err) {
1602: ntfs_err(sb, "Failed to read $UpCase (%d).", err);
1603: goto put_inode_out;
1604: }
1605:
1606: #ifdef __BIG_ENDIAN
1607: {
1608: u16 *dst = sbi->upcase;
1609:
1610: for (i = 0; i < 0x10000; i++)
1611: __swab16s(dst++);
1612: }
1613: #endif
1614:
1615: shared = ntfs_set_shared(sbi->upcase, 0x10000 * sizeof(short));
1616: if (shared && sbi->upcase != shared) {
1617: kvfree(sbi->upcase);
1618: sbi->upcase = shared;
1619: }
1620:
1621: iput(inode);
1622:
1623: if (is_ntfs3(sbi)) {
1624: /* Load $Secure. */
1625: err = ntfs_security_init(sbi);
1626: if (err) {
1627: ntfs_err(sb, "Failed to initialize $Secure (%d).", err);
1628: goto out;
1629: }
1630:
1631: /* Load $Extend. */
1632: err = ntfs_extend_init(sbi);
1633: if (err) {
1634: ntfs_warn(sb, "Failed to initialize $Extend.");
1635: goto load_root;
1636: }
1637:
1638: /* Load $Extend/$Reparse. */
1639: err = ntfs_reparse_init(sbi);
1640: if (err) {
1641: ntfs_warn(sb, "Failed to initialize $Extend/$Reparse.");
1642: goto load_root;
1643: }
1644:
1645: /* Load $Extend/$ObjId. */
1646: err = ntfs_objid_init(sbi);
1647: if (err) {
1648: ntfs_warn(sb, "Failed to initialize $Extend/$ObjId.");
1649: goto load_root;
1650: }
1651: }
1652:
1653: load_root:
1654: /* Load root. */
1655: ref.low = cpu_to_le32(MFT_REC_ROOT);
1656: ref.seq = cpu_to_le16(MFT_REC_ROOT);
1657: inode = ntfs_iget5(sb, &ref, &NAME_ROOT);
1658: if (IS_ERR(inode)) {
1659: err = PTR_ERR(inode);
1660: ntfs_err(sb, "Failed to load root (%d).", err);
1661: goto out;
1662: }
1663:
1664: /*
1665: * Final check. Looks like this case should never occurs.
1666: */
1667: if (!inode->i_op) {
1668: err = -EINVAL;
1669: ntfs_err(sb, "Failed to load root (%d).", err);
1670: goto put_inode_out;
1671: }
1672:
1673: sb->s_root = d_make_root(inode);
1674: if (!sb->s_root) {
1675: err = -ENOMEM;
1676: goto put_inode_out;
1677: }
1678:
1679: if (boot2) {
1680: /*
1681: * Alternative boot is ok but primary is not ok.
1682: * Volume is recognized as NTFS. Update primary boot.
1683: */
1684: struct buffer_head *bh0 = sb_getblk(sb, 0);
1685: if (bh0) {
1686: wait_on_buffer(bh0);
1687: lock_buffer(bh0);
1688: memcpy(bh0->b_data, boot2, sizeof(*boot2));
1689: set_buffer_uptodate(bh0);
1690: mark_buffer_dirty(bh0);
1691: unlock_buffer(bh0);
1692: if (!sync_dirty_buffer(bh0))
1693: ntfs_warn(sb, "primary boot is updated");
1694: put_bh(bh0);
1695: }
1696:
1697: kfree(boot2);
1698: }
1699:
1700: ntfs_create_procdir(sb);
1701:
1702: if (is_legacy_ntfs(sb))
1703: sb->s_flags |= SB_RDONLY;
1704: return 0;
1705:
1706: put_inode_out:
1707: iput(inode);
1708: out:
1709: /* sbi->options == options */
1710: if (options) {
1711: put_mount_options(sbi->options);
1712: sbi->options = NULL;
1713: }
1714:
1715: ntfs3_put_sbi(sbi);
1716: kfree(boot2);
1717: return err;
1718: }
SourceFile:fs/ntfs3/super.c]
|
| 18/2 |
2026/05/17 01:31 |
llm |
expert |
0m
Model:
Tokens:
input: 39007
output: 21
thoughts: 682
Thoughts: **Benign Uninitialized Value in NTFS3: A Deep Dive**
Okay, so I've just analyzed this KMSAN uninit-value report and, frankly, it's not a major security concern, though it's still worth understanding the root cause. My primary focus is on how this plays out in terms of actual system behavior, and I've dissected the code path pretty thoroughly.
The problem centers around an uninitialized value, `lcn`, within `ntfs_iomap_begin`. It gets passed by reference, and the critical point is within `attr_data_get_block`. If a certain condition is met β specifically, if `run_lookup_entry` returns false, and the subsequent logic leads to an early return β `lcn` remains uninitialized.
Now, here's where it gets interesting. Down the call stack, the function `ntfs_iomap_begin` eventually checks `lcn` against `EOF_LCN` and `RESIDENT_LCN`. This check could potentially lead down a branch, but crucially, it always validates `clen` (which is derived from `*len`, set earlier in the call stack). `clen` is set to 0, which means any comparison involving `clen` will always result in a return. This means the uninitialized `lcn` isn't actually *used* to access memory or perform any potentially dangerous operations. It just results in a return with `-EFAULT` or `-EINVAL`.
In effect, all this does is trigger a mount failure. The mount will fail because an error is propagated up the stack, and ultimately, it's just handled by a simple error message that appears in the logs. This is all triggered by `inode_read_data`, as it's the point where this uninitialized value can cause an issue.
The KMSAN report is valid, but the impact is limited. The system will fail to mount a corrupted filesystem, which is expected. No memory corruption, no information leak, no denial of service beyond the expected mount failure. I do need to determine whether a user can trigger it through a user namespace mount, since mounting a filesystem needs `CAP_SYS_ADMIN`, or an equivalent permission.
I need to check to see if `ntfs3` is configured to allow user namespace mounts. It's time to check the flags.
|
| 19/2 |
2026/05/17 01:31 |
tool |
grepper |
0m
Args: map[Expression:FS_USERNS_MOUNT]
Results: map[Output:drivers/android/binder/rust_binderfs.c=753=static struct file_system_type binder_fs_type = {
--
drivers/android/binder/rust_binderfs.c-757- .kill_sb = binderfs_kill_super,
drivers/android/binder/rust_binderfs.c:758: .fs_flags = FS_USERNS_MOUNT,
drivers/android/binder/rust_binderfs.c-759-};
--
drivers/android/binderfs.c=749=static struct file_system_type binder_fs_type = {
--
drivers/android/binderfs.c-753- .kill_sb = binderfs_kill_super,
drivers/android/binderfs.c:754: .fs_flags = FS_USERNS_MOUNT,
drivers/android/binderfs.c-755-};
--
fs/binfmt_misc.c=1021=static struct file_system_type bm_fs_type = {
--
fs/binfmt_misc.c-1024- .init_fs_context = bm_init_fs_context,
fs/binfmt_misc.c:1025: .fs_flags = FS_USERNS_MOUNT,
fs/binfmt_misc.c-1026- .kill_sb = kill_anon_super,
--
fs/devpts/inode.c=453=static struct file_system_type devpts_fs_type = {
--
fs/devpts/inode.c-457- .kill_sb = devpts_kill_sb,
fs/devpts/inode.c:458: .fs_flags = FS_USERNS_MOUNT,
fs/devpts/inode.c-459-};
--
fs/fuse/inode.c=2130=static struct file_system_type fuse_fs_type = {
--
fs/fuse/inode.c-2132- .name = "fuse",
fs/fuse/inode.c:2133: .fs_flags = FS_HAS_SUBTYPE | FS_USERNS_MOUNT | FS_ALLOW_IDMAP,
fs/fuse/inode.c-2134- .init_fs_context = fuse_init_fs_context,
--
fs/overlayfs/params.c=760=static const struct fs_context_operations ovl_context_ops = {
--
fs/overlayfs/params.c-769- * This is called during fsopen() and will record the user namespace of
fs/overlayfs/params.c:770: * the caller in fc->user_ns since we've raised FS_USERNS_MOUNT. We'll
fs/overlayfs/params.c-771- * need it when we actually create the superblock to verify that the
--
fs/overlayfs/super.c=1575=struct file_system_type ovl_fs_type = {
--
fs/overlayfs/super.c-1579- .parameters = ovl_parameter_spec,
fs/overlayfs/super.c:1580: .fs_flags = FS_USERNS_MOUNT,
fs/overlayfs/super.c-1581- .kill_sb = kill_anon_super,
--
fs/proc/root.c=357=static struct file_system_type proc_fs_type = {
--
fs/proc/root.c-361- .kill_sb = proc_kill_sb,
fs/proc/root.c:362: .fs_flags = FS_USERNS_MOUNT | FS_DISALLOW_NOTIFY_PERM,
fs/proc/root.c-363-};
--
fs/ramfs/inode.c=317=static struct file_system_type ramfs_fs_type = {
--
fs/ramfs/inode.c-321- .kill_sb = ramfs_kill_sb,
fs/ramfs/inode.c:322: .fs_flags = FS_USERNS_MOUNT,
fs/ramfs/inode.c-323-};
--
fs/super.c=694=bool mount_capable(struct fs_context *fc)
fs/super.c-695-{
fs/super.c:696: if (!(fc->fs_type->fs_flags & FS_USERNS_MOUNT))
fs/super.c-697- return capable(CAP_SYS_ADMIN);
--
fs/super.c=734=struct super_block *sget_fc(struct fs_context *fc,
--
fs/super.c-743- /*
fs/super.c:744: * Never allow s_user_ns != &init_user_ns when FS_USERNS_MOUNT is
fs/super.c-745- * not set, as the filesystem is likely unprepared to handle it.
--
fs/super.c-748- */
fs/super.c:749: if (user_ns != &init_user_ns && !(fc->fs_type->fs_flags & FS_USERNS_MOUNT)) {
fs/super.c-750- errorfc(fc, "VFS: Mounting from non-initial user namespace is not allowed");
--
fs/sysfs/mount.c=90=static struct file_system_type sysfs_fs_type = {
--
fs/sysfs/mount.c-93- .kill_sb = sysfs_kill_sb,
fs/sysfs/mount.c:94: .fs_flags = FS_USERNS_MOUNT,
fs/sysfs/mount.c-95-};
--
include/linux/fs.h=2271=struct file_system_type {
--
include/linux/fs.h-2276-#define FS_HAS_SUBTYPE 4
include/linux/fs.h:2277:#define FS_USERNS_MOUNT 8 /* Can be mounted by userns root */
include/linux/fs.h-2278-#define FS_DISALLOW_NOTIFY_PERM 16 /* Disable fanotify permission events */
--
ipc/mqueue.c=1613=static struct file_system_type mqueue_fs_type = {
--
ipc/mqueue.c-1616- .kill_sb = kill_anon_super,
ipc/mqueue.c:1617: .fs_flags = FS_USERNS_MOUNT,
ipc/mqueue.c-1618-};
--
kernel/bpf/inode.c=1074=static struct file_system_type bpf_fs_type = {
--
kernel/bpf/inode.c-1079- .kill_sb = bpf_kill_super,
kernel/bpf/inode.c:1080: .fs_flags = FS_USERNS_MOUNT,
kernel/bpf/inode.c-1081-};
--
kernel/cgroup/cgroup.c=2392=struct file_system_type cgroup_fs_type = {
--
kernel/cgroup/cgroup.c-2396- .kill_sb = cgroup_kill_sb,
kernel/cgroup/cgroup.c:2397: .fs_flags = FS_USERNS_MOUNT,
kernel/cgroup/cgroup.c-2398-};
--
kernel/cgroup/cgroup.c=2400=static struct file_system_type cgroup2_fs_type = {
--
kernel/cgroup/cgroup.c-2404- .kill_sb = cgroup_kill_sb,
kernel/cgroup/cgroup.c:2405: .fs_flags = FS_USERNS_MOUNT,
kernel/cgroup/cgroup.c-2406-};
--
kernel/cgroup/cgroup.c=2473=static struct file_system_type cpuset_fs_type = {
--
kernel/cgroup/cgroup.c-2476- .parameters = cpuset_fs_parameters,
kernel/cgroup/cgroup.c:2477: .fs_flags = FS_USERNS_MOUNT,
kernel/cgroup/cgroup.c-2478-};
--
mm/shmem.c=5351=static struct file_system_type shmem_fs_type = {
--
mm/shmem.c-5358- .kill_sb = kill_anon_super,
mm/shmem.c:5359: .fs_flags = FS_USERNS_MOUNT | FS_ALLOW_IDMAP | FS_MGTIME,
mm/shmem.c-5360-};
--
mm/shmem.c=5761=static struct file_system_type shmem_fs_type = {
--
mm/shmem.c-5765- .kill_sb = ramfs_kill_sb,
mm/shmem.c:5766: .fs_flags = FS_USERNS_MOUNT,
mm/shmem.c-5767-};
]
|
| 20/2 |
2026/05/17 01:31 |
llm |
expert |
0m
Model:
Tokens:
input: 42530
output: 25
thoughts: 446
Thoughts: **Analyzing the NTFS3 Filesystem Mounting Vulnerability**
Okay, so `ntfs3` isn't listed among the filesystems that support `FS_USERNS_MOUNT`. This means, as I understand it, you can't just mount it from within a user namespace. It needs `CAP_SYS_ADMIN` in the initial namespace, effectively making it inaccessible to unprivileged processes or user namespaces in a default configuration.
The vulnerability comes into play if you've got auto-mounting configured, like with something such as udisks2 on a desktop, or if root is doing the mounting. But here's where it gets interesting... the syzkaller reproducer mounts it. Now, syzkaller usually operates as root or within a user namespace. If it's in a user namespace, how is it pulling this off?
Hmm, there are a few possibilities. Syzkaller could be running as root in the initial namespace, or maybe there's a kernel patch enabling all filesystems to be mounted in user namespaces. Syzkaller does stuff like that sometimes, or maybe `ntfs3` got mounted through a loop device by root.
Wait, the reproducer's code shows `syz_mount_image`, which is using a loop device and then calling `mount`. So, if syzkaller is running as root, it can just mount it directly.
But, for this analysis, we are assuming a standard kernel configuration. Under that assumption, `ntfs3` *shouldn't* have `FS_USERNS_MOUNT`. Therefore, it *shouldn't* be accessible from user namespaces.
Alright, let's just make sure, I need to check `fs/ntfs3/super.c` to be certain.
|
| 21/2 |
2026/05/17 01:31 |
tool |
grepper |
0m
Error:
Args: map[Expression:FS_USERNS_MOUNT.*ntfs3]
Results:
|
| 22/2 |
2026/05/17 01:31 |
llm |
expert |
0m
Model:
Tokens:
input: 43390
output: 24
thoughts: 23
Thoughts: Okay, here's my summary, taking the perspective of someone familiar with kernel file system code:
**Diving into the NTFS3 Superblock**
Alright, time to get down to brass tacks. I need to understand how the NTFS3 file system type is defined within the kernel. My immediate thought is to go straight to the source. Specifically, I need to check out `fs/ntfs3/super.c`. That's where I expect to find the core definitions related to the file system's superblock data structures and, consequently, the `file_system_type` structure associated with NTFS3. It's the logical place to start digging for the crucial details I need. Let's see what's what.
|
| 23/2 |
2026/05/17 01:32 |
tool |
grepper |
0m
Error:
Args: map[Expression:struct file_system_type.*ntfs3]
Results:
|
| 24/2 |
2026/05/17 01:32 |
llm |
expert |
0m
Model:
Tokens:
input: 43605
output: 20
thoughts: 23
Thoughts: Okay, here's my summary, taking the perspective of someone familiar with kernel file system code:
**Diving into the NTFS3 Superblock**
Alright, time to get down to brass tacks. I need to understand how the NTFS3 file system type is defined within the kernel. My immediate thought is to go straight to the source. Specifically, I need to check out `fs/ntfs3/super.c`. That's where I expect to find the core definitions related to the file system's superblock data structures and, consequently, the `file_system_type` structure associated with NTFS3. It's the logical place to start digging for the crucial details I need. Let's see what's what.
|
| 25/2 |
2026/05/17 01:32 |
tool |
grepper |
0m
Args: map[Expression:struct file_system_type]
Results: map[Output:
Full output is too long, showing 500 out of 1199 lines.
Use more precise expression if possible.
[Documentation/filesystems/mount_api.rst=65=context. This is represented by the fs_context structure::
--
Documentation/filesystems/mount_api.rst-68- const struct fs_context_operations *ops;
Documentation/filesystems/mount_api.rst:69: struct file_system_type *fs_type;
Documentation/filesystems/mount_api.rst-70- void *fs_private;
--
Documentation/filesystems/mount_api.rst=86=The fs_context fields are as follows:
--
Documentation/filesystems/mount_api.rst-97-
Documentation/filesystems/mount_api.rst:98: struct file_system_type *fs_type
Documentation/filesystems/mount_api.rst-99-
--
Documentation/filesystems/mount_api.rst=401=destroying a context:
--
Documentation/filesystems/mount_api.rst-404-
Documentation/filesystems/mount_api.rst:405: struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
Documentation/filesystems/mount_api.rst-406- unsigned int sb_flags);
--
Documentation/filesystems/mount_api.rst-430- struct fs_context *fs_context_for_submount(
Documentation/filesystems/mount_api.rst:431: struct file_system_type *fs_type,
Documentation/filesystems/mount_api.rst-432- struct dentry *reference);
--
Documentation/filesystems/porting.rst=64=informative error value to report). Call it foo_fill_super(). Now declare::
Documentation/filesystems/porting.rst-65-
Documentation/filesystems/porting.rst:66: int foo_get_sb(struct file_system_type *fs_type,
Documentation/filesystems/porting.rst-67- int flags, const char *dev_name, void *data, struct vfsmount *mnt)
--
Documentation/filesystems/vfs.rst=86=functions:
--
Documentation/filesystems/vfs.rst-91-
Documentation/filesystems/vfs.rst:92: extern int register_filesystem(struct file_system_type *);
Documentation/filesystems/vfs.rst:93: extern int unregister_filesystem(struct file_system_type *);
Documentation/filesystems/vfs.rst-94-
Documentation/filesystems/vfs.rst:95:The passed struct file_system_type describes your filesystem. When a
Documentation/filesystems/vfs.rst-96-request is made to mount a filesystem onto a directory in your
--
Documentation/filesystems/vfs.rst=102=file /proc/filesystems.
--
Documentation/filesystems/vfs.rst-104-
Documentation/filesystems/vfs.rst:105:struct file_system_type
Documentation/filesystems/vfs.rst-106------------------------
--
Documentation/filesystems/vfs.rst=109=members are defined:
--
Documentation/filesystems/vfs.rst-112-
Documentation/filesystems/vfs.rst:113: struct file_system_type {
Documentation/filesystems/vfs.rst-114- const char *name;
--
Documentation/filesystems/vfs.rst-119- struct module *owner;
Documentation/filesystems/vfs.rst:120: struct file_system_type * next;
Documentation/filesystems/vfs.rst-121- struct hlist_head fs_supers;
--
arch/powerpc/platforms/cell/spufs/inode.c=508=static int spufs_create_gang(struct inode *inode,
--
arch/powerpc/platforms/cell/spufs/inode.c-524-
arch/powerpc/platforms/cell/spufs/inode.c:525:static struct file_system_type spufs_type;
arch/powerpc/platforms/cell/spufs/inode.c-526-
--
arch/powerpc/platforms/cell/spufs/inode.c=725=static int spufs_init_fs_context(struct fs_context *fc)
--
arch/powerpc/platforms/cell/spufs/inode.c-752-
arch/powerpc/platforms/cell/spufs/inode.c:753:static struct file_system_type spufs_type = {
arch/powerpc/platforms/cell/spufs/inode.c-754- .owner = THIS_MODULE,
--
arch/s390/hypfs/inode.c=43=static const struct file_operations hypfs_file_ops;
arch/s390/hypfs/inode.c:44:static struct file_system_type hypfs_type;
arch/s390/hypfs/inode.c-45-static const struct super_operations hypfs_s_ops;
--
arch/s390/hypfs/inode.c=413=static const struct file_operations hypfs_file_ops = {
--
arch/s390/hypfs/inode.c-419-
arch/s390/hypfs/inode.c:420:static struct file_system_type hypfs_type = {
arch/s390/hypfs/inode.c-421- .owner = THIS_MODULE,
--
arch/um/drivers/mconsole_kern.c=694=static int __init mount_proc(void)
arch/um/drivers/mconsole_kern.c-695-{
arch/um/drivers/mconsole_kern.c:696: struct file_system_type *proc_fs_type;
arch/um/drivers/mconsole_kern.c-697- struct vfsmount *mnt;
--
block/bdev.c=435=static int bd_init_fs_context(struct fs_context *fc)
--
block/bdev.c-444-
block/bdev.c:445:static struct file_system_type bd_type = {
block/bdev.c-446- .name = "bdev",
--
drivers/android/binder/rust_binderfs.c=737=static void binderfs_kill_super(struct super_block *sb)
--
drivers/android/binder/rust_binderfs.c-752-
drivers/android/binder/rust_binderfs.c:753:static struct file_system_type binder_fs_type = {
drivers/android/binder/rust_binderfs.c-754- .name = "binder",
--
drivers/android/binderfs.c=733=static void binderfs_kill_super(struct super_block *sb)
--
drivers/android/binderfs.c-748-
drivers/android/binderfs.c:749:static struct file_system_type binder_fs_type = {
drivers/android/binderfs.c-750- .name = "binder",
--
drivers/base/devtmpfs.c=63=static struct vfsmount *mnt;
drivers/base/devtmpfs.c-64-
drivers/base/devtmpfs.c:65:static struct file_system_type internal_fs_type = {
drivers/base/devtmpfs.c-66- .name = "devtmpfs",
--
drivers/base/devtmpfs.c=90=static int devtmpfs_init_fs_context(struct fs_context *fc)
--
drivers/base/devtmpfs.c-105-
drivers/base/devtmpfs.c:106:static struct file_system_type dev_fs_type = {
drivers/base/devtmpfs.c-107- .name = "devtmpfs",
--
drivers/dax/super.c=394=static int dax_init_fs_context(struct fs_context *fc)
--
drivers/dax/super.c-402-
drivers/dax/super.c:403:static struct file_system_type dax_fs_type = {
drivers/dax/super.c-404- .name = "dax",
--
drivers/dma-buf/dma-buf.c=211=static int dma_buf_fs_init_context(struct fs_context *fc)
--
drivers/dma-buf/dma-buf.c-221-
drivers/dma-buf/dma-buf.c:222:static struct file_system_type dma_buf_fs_type = {
drivers/dma-buf/dma-buf.c-223- .name = "dmabuf",
--
drivers/gpu/drm/drm_drv.c=623=static int drm_fs_init_fs_context(struct fs_context *fc)
--
drivers/gpu/drm/drm_drv.c-627-
drivers/gpu/drm/drm_drv.c:628:static struct file_system_type drm_fs_type = {
drivers/gpu/drm/drm_drv.c-629- .name = "drm",
--
drivers/gpu/drm/drm_gem.c=112=int drm_gem_huge_mnt_create(struct drm_device *dev, const char *value)
drivers/gpu/drm/drm_gem.c-113-{
drivers/gpu/drm/drm_gem.c:114: struct file_system_type *type;
drivers/gpu/drm/drm_gem.c-115- struct fs_context *fc;
--
drivers/misc/ibmasm/ibmasmfs.c=95=static const struct super_operations ibmasmfs_s_ops = {
--
drivers/misc/ibmasm/ibmasmfs.c-99-
drivers/misc/ibmasm/ibmasmfs.c:100:static struct file_system_type ibmasmfs_type = {
drivers/misc/ibmasm/ibmasmfs.c-101- .owner = THIS_MODULE,
--
drivers/usb/gadget/function/f_fs.c=2086=ffs_fs_kill_sb(struct super_block *sb)
--
drivers/usb/gadget/function/f_fs.c-2099-
drivers/usb/gadget/function/f_fs.c:2100:static struct file_system_type ffs_fs_type = {
drivers/usb/gadget/function/f_fs.c-2101- .owner = THIS_MODULE,
--
drivers/usb/gadget/legacy/inode.c=2099=gadgetfs_kill_sb (struct super_block *sb)
--
drivers/usb/gadget/legacy/inode.c-2113-
drivers/usb/gadget/legacy/inode.c:2114:static struct file_system_type gadgetfs_type = {
drivers/usb/gadget/legacy/inode.c-2115- .owner = THIS_MODULE,
--
drivers/vfio/vfio_main.c=242=static int vfio_fs_init_fs_context(struct fs_context *fc)
--
drivers/vfio/vfio_main.c-246-
drivers/vfio/vfio_main.c:247:static struct file_system_type vfio_fs_type = {
drivers/vfio/vfio_main.c-248- .name = "vfio",
--
drivers/xen/xenfs/super.c=81=static int xenfs_init_fs_context(struct fs_context *fc)
--
drivers/xen/xenfs/super.c-86-
drivers/xen/xenfs/super.c:87:static struct file_system_type xenfs_type = {
drivers/xen/xenfs/super.c-88- .owner = THIS_MODULE,
--
fs/9p/v9fs_vfs.h-30-
fs/9p/v9fs_vfs.h:31:extern struct file_system_type v9fs_fs_type;
fs/9p/v9fs_vfs.h-32-extern const struct address_space_operations v9fs_addr_operations;
--
fs/9p/vfs_super.c=307=static int v9fs_init_fs_context(struct fs_context *fc)
--
fs/9p/vfs_super.c-356-
fs/9p/vfs_super.c:357:struct file_system_type v9fs_fs_type = {
fs/9p/vfs_super.c-358- .name = "9p",
--
fs/adfs/super.c=436=static int adfs_init_fs_context(struct fs_context *fc)
--
fs/adfs/super.c-464-
fs/adfs/super.c:465:static struct file_system_type adfs_fs_type = {
fs/adfs/super.c-466- .owner = THIS_MODULE,
--
fs/affs/super.c=614=static int affs_init_fs_context(struct fs_context *fc)
--
fs/affs/super.c-646-
fs/affs/super.c:647:static struct file_system_type affs_fs_type = {
fs/affs/super.c-648- .owner = THIS_MODULE,
--
fs/afs/internal.h=257=static inline struct afs_super_info *AFS_FS_S(struct super_block *sb)
--
fs/afs/internal.h-261-
fs/afs/internal.h:262:extern struct file_system_type afs_fs_type;
fs/afs/internal.h-263-
--
fs/afs/super.c=41=static const struct fs_parameter_spec afs_fs_parameters[];
fs/afs/super.c-42-
fs/afs/super.c:43:struct file_system_type afs_fs_type = {
fs/afs/super.c-44- .owner = THIS_MODULE,
--
fs/aio.c=290=static int __init aio_setup(void)
fs/aio.c-291-{
fs/aio.c:292: static struct file_system_type aio_fs = {
fs/aio.c-293- .name = "aio",
--
fs/anon_inodes.c=84=static int anon_inodefs_init_fs_context(struct fs_context *fc)
--
fs/anon_inodes.c-94-
fs/anon_inodes.c:95:static struct file_system_type anon_inode_fs_type = {
fs/anon_inodes.c-96- .name = "anon_inodefs",
--
fs/autofs/autofs_i.h-47-
fs/autofs/autofs_i.h:48:extern struct file_system_type autofs_fs_type;
fs/autofs/autofs_i.h-49-
--
fs/autofs/init.c-9-
fs/autofs/init.c:10:struct file_system_type autofs_fs_type = {
fs/autofs/init.c-11- .owner = THIS_MODULE,
--
fs/befs/linuxvfs.c=973=static void befs_free_fc(struct fs_context *fc)
--
fs/befs/linuxvfs.c-980-
fs/befs/linuxvfs.c:981:static struct file_system_type befs_fs_type = {
fs/befs/linuxvfs.c-982- .owner = THIS_MODULE,
--
fs/bfs/inode.c=477=static int bfs_init_fs_context(struct fs_context *fc)
--
fs/bfs/inode.c-483-
fs/bfs/inode.c:484:static struct file_system_type bfs_fs_type = {
fs/bfs/inode.c-485- .owner = THIS_MODULE,
--
fs/binfmt_misc.c=50=typedef struct {
--
fs/binfmt_misc.c-63-
fs/binfmt_misc.c:64:static struct file_system_type bm_fs_type;
fs/binfmt_misc.c-65-
--
fs/binfmt_misc.c=1016=static struct linux_binfmt misc_format = {
--
fs/binfmt_misc.c-1020-
fs/binfmt_misc.c:1021:static struct file_system_type bm_fs_type = {
fs/binfmt_misc.c-1022- .owner = THIS_MODULE,
--
fs/btrfs/super.c=66=static const struct super_operations btrfs_super_ops;
fs/btrfs/super.c:67:static struct file_system_type btrfs_fs_type;
fs/btrfs/super.c-68-
--
fs/btrfs/super.c=2172=static int btrfs_init_fs_context(struct fs_context *fc)
--
fs/btrfs/super.c-2200-
fs/btrfs/super.c:2201:static struct file_system_type btrfs_fs_type = {
fs/btrfs/super.c-2202- .owner = THIS_MODULE,
--
fs/btrfs/tests/btrfs-tests.c=42=static int btrfs_test_init_fs_context(struct fs_context *fc)
--
fs/btrfs/tests/btrfs-tests.c-50-
fs/btrfs/tests/btrfs-tests.c:51:static struct file_system_type test_type = {
fs/btrfs/tests/btrfs-tests.c-52- .name = "btrfs_test_fs",
--
fs/ceph/super.c=1527=static void ceph_kill_sb(struct super_block *s)
--
fs/ceph/super.c-1591-
fs/ceph/super.c:1592:static struct file_system_type ceph_fs_type = {
fs/ceph/super.c-1593- .owner = THIS_MODULE,
--
fs/coda/coda_int.h=6=struct file;
fs/coda/coda_int.h-7-
fs/coda/coda_int.h:8:extern struct file_system_type coda_fs_type;
fs/coda/coda_int.h-9-extern unsigned long coda_timeout;
--
fs/coda/inode.c=380=static int coda_init_fs_context(struct fs_context *fc)
--
fs/coda/inode.c-392-
fs/coda/inode.c:393:struct file_system_type coda_fs_type = {
fs/coda/inode.c-394- .owner = THIS_MODULE,
--
fs/configfs/mount.c=109=static int configfs_init_fs_context(struct fs_context *fc)
--
fs/configfs/mount.c-114-
fs/configfs/mount.c:115:static struct file_system_type configfs_fs_type = {
fs/configfs/mount.c-116- .owner = THIS_MODULE,
--
fs/cramfs/inode.c=975=static int cramfs_init_fs_context(struct fs_context *fc)
--
fs/cramfs/inode.c-980-
fs/cramfs/inode.c:981:static struct file_system_type cramfs_fs_type = {
fs/cramfs/inode.c-982- .owner = THIS_MODULE,
--
fs/debugfs/inode.c=309=static int debugfs_init_fs_context(struct fs_context *fc)
--
fs/debugfs/inode.c-323-
fs/debugfs/inode.c:324:static struct file_system_type debug_fs_type = {
fs/debugfs/inode.c-325- .owner = THIS_MODULE,
--
fs/devpts/inode.c=443=static void devpts_kill_sb(struct super_block *sb)
--
fs/devpts/inode.c-452-
fs/devpts/inode.c:453:static struct file_system_type devpts_fs_type = {
fs/devpts/inode.c-454- .name = "devpts",
--
fs/ecryptfs/main.c=428=struct kmem_cache *ecryptfs_sb_info_cache;
fs/ecryptfs/main.c:429:static struct file_system_type ecryptfs_fs_type;
fs/ecryptfs/main.c-430-
--
fs/ecryptfs/main.c=608=static int ecryptfs_init_fs_context(struct fs_context *fc)
--
fs/ecryptfs/main.c-630-
fs/ecryptfs/main.c:631:static struct file_system_type ecryptfs_fs_type = {
fs/ecryptfs/main.c-632- .owner = THIS_MODULE,
--
fs/efivarfs/super.c=410=static int efivarfs_check_missing(efi_char16_t *name16, efi_guid_t vendor,
--
fs/efivarfs/super.c-445-
fs/efivarfs/super.c:446:static struct file_system_type efivarfs_type;
fs/efivarfs/super.c-447-
--
fs/efivarfs/super.c=521=static void efivarfs_kill_sb(struct super_block *sb)
--
fs/efivarfs/super.c-530-
fs/efivarfs/super.c:531:static struct file_system_type efivarfs_type = {
fs/efivarfs/super.c-532- .owner = THIS_MODULE,
--
fs/efs/super.c=32=static struct pt_types sgi_pt_types[] = {
--
fs/efs/super.c-53- */
fs/efs/super.c:54:static struct file_system_type efs_fs_type = {
fs/efs/super.c-55- .owner = THIS_MODULE,
--
fs/erofs/internal.h=185=static inline bool erofs_is_fileio_mode(struct erofs_sb_info *sbi)
--
fs/erofs/internal.h-189-
fs/erofs/internal.h:190:extern struct file_system_type erofs_anon_fs_type;
fs/erofs/internal.h-191-
--
fs/erofs/super.c=952=static void erofs_put_super(struct super_block *sb)
--
fs/erofs/super.c-964-
fs/erofs/super.c:965:static struct file_system_type erofs_fs_type = {
fs/erofs/super.c-966- .owner = THIS_MODULE,
--
fs/erofs/super.c=991=static int erofs_anon_init_fs_context(struct fs_context *fc)
--
fs/erofs/super.c-1001-
fs/erofs/super.c:1002:struct file_system_type erofs_anon_fs_type = {
fs/erofs/super.c-1003- .name = "pseudo_erofs",
--
fs/exfat/super.c=860=static void exfat_kill_sb(struct super_block *sb)
--
fs/exfat/super.c-868-
fs/exfat/super.c:869:static struct file_system_type exfat_fs_type = {
fs/exfat/super.c-870- .owner = THIS_MODULE,
--
fs/ext2/super.c=1669=static int ext2_init_fs_context(struct fs_context *fc)
--
fs/ext2/super.c-1697-
fs/ext2/super.c:1698:static struct file_system_type ext2_fs_type = {
fs/ext2/super.c-1699- .owner = THIS_MODULE,
--
fs/ext4/extents-test.c=133=static int ext_set(struct super_block *sb, void *data)
--
fs/ext4/extents-test.c-137-
fs/ext4/extents-test.c:138:static struct file_system_type ext_fs_type = {
fs/ext4/extents-test.c-139- .name = "extents test",
--
fs/ext4/mballoc-test.c=60=static void mbt_kill_sb(struct super_block *sb)
--
fs/ext4/mballoc-test.c-64-
fs/ext4/mballoc-test.c:65:static struct file_system_type mbt_fs_type = {
fs/ext4/mballoc-test.c-66- .name = "mballoc test",
--
fs/ext4/super.c=125=static const struct fs_context_operations ext4_context_ops = {
--
fs/ext4/super.c-133-#if !defined(CONFIG_EXT2_FS) && !defined(CONFIG_EXT2_FS_MODULE) && defined(CONFIG_EXT4_USE_FOR_EXT2)
fs/ext4/super.c:134:static struct file_system_type ext2_fs_type = {
fs/ext4/super.c-135- .owner = THIS_MODULE,
--
fs/ext4/super.c=143=MODULE_ALIAS("ext2");
--
fs/ext4/super.c-149-
fs/ext4/super.c:150:static struct file_system_type ext3_fs_type = {
fs/ext4/super.c-151- .owner = THIS_MODULE,
--
fs/ext4/super.c=7456=static void ext4_kill_sb(struct super_block *sb)
--
fs/ext4/super.c-7466-
fs/ext4/super.c:7467:static struct file_system_type ext4_fs_type = {
fs/ext4/super.c-7468- .owner = THIS_MODULE,
--
fs/f2fs/super.c=5508=static int f2fs_init_fs_context(struct fs_context *fc)
--
fs/f2fs/super.c-5521-
fs/f2fs/super.c:5522:static struct file_system_type f2fs_fs_type = {
fs/f2fs/super.c-5523- .owner = THIS_MODULE,
--
fs/fat/namei_msdos.c=677=static int msdos_init_fs_context(struct fs_context *fc)
--
fs/fat/namei_msdos.c-689-
fs/fat/namei_msdos.c:690:static struct file_system_type msdos_fs_type = {
fs/fat/namei_msdos.c-691- .owner = THIS_MODULE,
--
fs/fat/namei_vfat.c=1222=static int vfat_init_fs_context(struct fs_context *fc)
--
fs/fat/namei_vfat.c-1234-
fs/fat/namei_vfat.c:1235:static struct file_system_type vfat_fs_type = {
fs/fat/namei_vfat.c-1236- .owner = THIS_MODULE,
--
fs/filesystems.c-33-
fs/filesystems.c:34:static struct file_system_type *file_systems;
fs/filesystems.c-35-static DEFINE_RWLOCK(file_systems_lock);
--
fs/filesystems.c-37-/* WARNING: This can be used only if we _already_ own a reference */
fs/filesystems.c:38:struct file_system_type *get_filesystem(struct file_system_type *fs)
fs/filesystems.c-39-{
--
fs/filesystems.c-43-
fs/filesystems.c:44:void put_filesystem(struct file_system_type *fs)
fs/filesystems.c-45-{
--
fs/filesystems.c-48-
fs/filesystems.c:49:static struct file_system_type **find_filesystem(const char *name, unsigned len)
fs/filesystems.c-50-{
fs/filesystems.c:51: struct file_system_type **p;
fs/filesystems.c-52- for (p = &file_systems; *p; p = &(*p)->next)
--
fs/filesystems.c-66- *
fs/filesystems.c:67: * The &struct file_system_type that is passed is linked into the kernel
fs/filesystems.c-68- * structures and must not be freed until the file system has been
--
fs/filesystems.c-71-
fs/filesystems.c:72:int register_filesystem(struct file_system_type * fs)
fs/filesystems.c-73-{
fs/filesystems.c-74- int res = 0;
fs/filesystems.c:75: struct file_system_type ** p;
fs/filesystems.c-76-
--
fs/filesystems.c=94=EXPORT_SYMBOL(register_filesystem);
--
fs/filesystems.c-103- *
fs/filesystems.c:104: * Once this function has returned the &struct file_system_type structure
fs/filesystems.c-105- * may be freed or reused.
--
fs/filesystems.c-107-
fs/filesystems.c:108:int unregister_filesystem(struct file_system_type * fs)
fs/filesystems.c-109-{
fs/filesystems.c:110: struct file_system_type ** tmp;
fs/filesystems.c-111-
--
fs/filesystems.c=132=static int fs_index(const char __user * __name)
fs/filesystems.c-133-{
fs/filesystems.c:134: struct file_system_type * tmp;
fs/filesystems.c-135- char *name __free(kfree) = strndup_user(__name, PATH_MAX);
--
fs/filesystems.c=153=static int fs_name(unsigned int index, char __user * buf)
fs/filesystems.c-154-{
fs/filesystems.c:155: struct file_system_type * tmp;
fs/filesystems.c-156- int len, res = -EINVAL;
--
fs/filesystems.c=177=static int fs_maxindex(void)
fs/filesystems.c-178-{
fs/filesystems.c:179: struct file_system_type * tmp;
fs/filesystems.c-180- int index;
--
fs/filesystems.c=213=int __init list_bdev_fs_names(char *buf, size_t size)
fs/filesystems.c-214-{
fs/filesystems.c:215: struct file_system_type *p;
fs/filesystems.c-216- size_t len;
--
fs/filesystems.c=238=static int filesystems_proc_show(struct seq_file *m, void *v)
fs/filesystems.c-239-{
fs/filesystems.c:240: struct file_system_type * tmp;
fs/filesystems.c-241-
--
fs/filesystems.c=259=module_init(proc_filesystems_init);
--
fs/filesystems.c-261-
fs/filesystems.c:262:static struct file_system_type *__get_fs_type(const char *name, int len)
fs/filesystems.c-263-{
fs/filesystems.c:264: struct file_system_type *fs;
fs/filesystems.c-265-
--
fs/filesystems.c-273-
fs/filesystems.c:274:struct file_system_type *get_fs_type(const char *name)
fs/filesystems.c-275-{
fs/filesystems.c:276: struct file_system_type *fs;
fs/filesystems.c-277- const char *dot = strchr(name, '.');
--
fs/freevxfs/vxfs_super.c=297=static int vxfs_init_fs_context(struct fs_context *fc)
--
fs/freevxfs/vxfs_super.c-303-
fs/freevxfs/vxfs_super.c:304:static struct file_system_type vxfs_fs_type = {
fs/freevxfs/vxfs_super.c-305- .owner = THIS_MODULE,
--
fs/fs_context.c=243=EXPORT_SYMBOL(generic_parse_monolithic);
--
fs/fs_context.c-257- */
fs/fs_context.c:258:static struct fs_context *alloc_fs_context(struct file_system_type *fs_type,
fs/fs_context.c-259- struct dentry *reference,
--
fs/fs_context.c-305-
fs/fs_context.c:306:struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
fs/fs_context.c-307- unsigned int sb_flags)
--
fs/fs_context.c=321=EXPORT_SYMBOL(fs_context_for_reconfigure);
--
fs/fs_context.c-330- */
fs/fs_context.c:331:struct fs_context *fs_context_for_submount(struct file_system_type *type,
]
]
|
| 26/2 |
2026/05/17 01:32 |
llm |
expert |
0m
Model:
Tokens:
input: 52662
output: 24
thoughts: 23
Thoughts: Okay, here's my summary, taking the perspective of someone familiar with kernel file system code:
**Diving into the NTFS3 Superblock**
Alright, time to get down to brass tacks. I need to understand how the NTFS3 file system type is defined within the kernel. My immediate thought is to go straight to the source. Specifically, I need to check out `fs/ntfs3/super.c`. That's where I expect to find the core definitions related to the file system's superblock data structures and, consequently, the `file_system_type` structure associated with NTFS3. It's the logical place to start digging for the crucial details I need. Let's see what's what.
|
| 27/2 |
2026/05/17 01:32 |
tool |
grepper |
0m
Error:
Args: map[Expression:struct file_system_type.*ntfs3]
Results:
|
| 28/2 |
2026/05/17 01:32 |
llm |
expert |
0m
Model:
Tokens:
input: 52877
output: 21
thoughts: 25
Thoughts: Here's my thought process, as if I were considering this myself:
**Investigating the Filesystem Identifier**
Okay, so the filesystem name I'm working with is `ntfs3`. My first instinct, being familiar with how these things are often structured in the kernel, is to look for the "fs_type" associated with it. I'm going to quickly use `grep` to hunt down the symbol `ntfs3_fs_type`. That will give me the entry point and where to start digging for info. Let's see what that yields!
|
| 29/2 |
2026/05/17 01:32 |
tool |
grepper |
0m
Error:
Args: map[Expression:ntfs3_fs_type]
Results:
|
| 30/2 |
2026/05/17 01:32 |
llm |
expert |
0m
Model:
Tokens:
input: 53058
output: 25
thoughts: 21
Thoughts: Okay, here's my interpretation of that thought process, as if it were my own:
**Investigating NTFS3 Filesystem Implementation**
Alright, I need to get a better handle on the `ntfs3` filesystem driver, specifically where it's handling file system types. Let me see... I'll jump right into the source code and use `grep` to quickly search for occurrences of "file_system_type". That should get me to the relevant areas in the `fs/ntfs3/` directory without wasting time manually sifting through everything. It's the fastest way to get a quick overview of how the driver identifies and works with the NTFS file system. Good starting point.
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tool |
grepper |
0m
Error:
Args: map[Expression:file_system_type.*fs/ntfs3]
Results:
|
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2026/05/17 01:32 |
llm |
expert |
0m
Model:
Tokens:
input: 53265
output: 19
thoughts: 24
Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience:
**Grep Hunt Begins: Diving into NTFS3**
Right, let's get down to brass tacks. I need to understand how the `file_system_type` is being handled within the NTFS3 file system code. My initial approach? Straight to the source. I'm going to `grep` for `file_system_type` directly within `fs/ntfs3/super.c`. No need for elaborate debugging sessions just yet; let's see what the immediate landscape looks like. This initial search should quickly reveal the direct references, any assignments, and how itβs being used to register or identify the NTFS3 file system. I'm hoping this will give me a solid starting point for tracing its use and understanding its purpose in the overall file system initialization and operation. After that, I will likely look for where it is declared.
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grepper |
0m
Args: map[Expression:file_system_type]
Results: map[Output:
Full output is too long, showing 500 out of 1265 lines.
Use more precise expression if possible.
[Documentation/filesystems/locking.rst=223=see also dquot_operations section.
Documentation/filesystems/locking.rst-224-
Documentation/filesystems/locking.rst:225:file_system_type
Documentation/filesystems/locking.rst-226-================
--
Documentation/filesystems/mount_api.rst=29=The creation of new mounts is now to be done in a multistep process:
--
Documentation/filesystems/mount_api.rst-46-
Documentation/filesystems/mount_api.rst:47:To support this, the file_system_type struct gains two new fields::
Documentation/filesystems/mount_api.rst-48-
--
Documentation/filesystems/mount_api.rst=65=context. This is represented by the fs_context structure::
--
Documentation/filesystems/mount_api.rst-68- const struct fs_context_operations *ops;
Documentation/filesystems/mount_api.rst:69: struct file_system_type *fs_type;
Documentation/filesystems/mount_api.rst-70- void *fs_private;
--
Documentation/filesystems/mount_api.rst=86=The fs_context fields are as follows:
--
Documentation/filesystems/mount_api.rst-92- These are operations that can be done on a filesystem context (see
Documentation/filesystems/mount_api.rst:93: below). This must be set by the ->init_fs_context() file_system_type
Documentation/filesystems/mount_api.rst-94- operation.
--
Documentation/filesystems/mount_api.rst-97-
Documentation/filesystems/mount_api.rst:98: struct file_system_type *fs_type
Documentation/filesystems/mount_api.rst-99-
Documentation/filesystems/mount_api.rst:100: A pointer to the file_system_type of the filesystem that is being
Documentation/filesystems/mount_api.rst-101- constructed or reconfigured. This retains a reference on the type owner.
--
Documentation/filesystems/mount_api.rst=401=destroying a context:
--
Documentation/filesystems/mount_api.rst-404-
Documentation/filesystems/mount_api.rst:405: struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
Documentation/filesystems/mount_api.rst-406- unsigned int sb_flags);
--
Documentation/filesystems/mount_api.rst-430- struct fs_context *fs_context_for_submount(
Documentation/filesystems/mount_api.rst:431: struct file_system_type *fs_type,
Documentation/filesystems/mount_api.rst-432- struct dentry *reference);
--
Documentation/filesystems/mount_api.rst=615=The members are as follows:
--
Documentation/filesystems/mount_api.rst-732-
Documentation/filesystems/mount_api.rst:733:The parser should be pointed to by the parser pointer in the file_system_type
Documentation/filesystems/mount_api.rst-734-struct as this will provide validation on registration (if
--
Documentation/filesystems/porting.rst=52=correctly.
--
Documentation/filesystems/porting.rst-57-
Documentation/filesystems/porting.rst:58:Change of file_system_type method (->read_super to ->get_sb)
Documentation/filesystems/porting.rst-59-
--
Documentation/filesystems/porting.rst=64=informative error value to report). Call it foo_fill_super(). Now declare::
Documentation/filesystems/porting.rst-65-
Documentation/filesystems/porting.rst:66: int foo_get_sb(struct file_system_type *fs_type,
Documentation/filesystems/porting.rst-67- int flags, const char *dev_name, void *data, struct vfsmount *mnt)
--
Documentation/filesystems/porting.rst=129=problems might be over...
--
Documentation/filesystems/porting.rst-134-
Documentation/filesystems/porting.rst:135:new file_system_type method - kill_sb(superblock). If you are converting
Documentation/filesystems/porting.rst-136-an existing filesystem, set it according to ->fs_flags::
--
Documentation/filesystems/porting.rst=980=The holder of a block device is now the superblock.
Documentation/filesystems/porting.rst-981-
Documentation/filesystems/porting.rst:982:The holder of a block device used to be the file_system_type which wasn't
Documentation/filesystems/porting.rst-983-particularly useful. It wasn't possible to go from block device to owning
--
Documentation/filesystems/porting.rst=988=In the old mechanism reusing or creating a superblock for a racing mount(2) and
Documentation/filesystems/porting.rst:989:umount(2) relied on the file_system_type as the holder. This was severely
Documentation/filesystems/porting.rst-990-underdocumented however:
--
Documentation/filesystems/porting.rst-1007-
Documentation/filesystems/porting.rst:1008:Because the holder of the block device was the file_system_type any concurrent
Documentation/filesystems/porting.rst-1009-mounter could open the block devices of any superblock of the same
Documentation/filesystems/porting.rst:1010:file_system_type without risking seeing EBUSY because the block device was
Documentation/filesystems/porting.rst-1011-still in use by another superblock.
--
Documentation/filesystems/vfs.rst=86=functions:
--
Documentation/filesystems/vfs.rst-91-
Documentation/filesystems/vfs.rst:92: extern int register_filesystem(struct file_system_type *);
Documentation/filesystems/vfs.rst:93: extern int unregister_filesystem(struct file_system_type *);
Documentation/filesystems/vfs.rst-94-
Documentation/filesystems/vfs.rst:95:The passed struct file_system_type describes your filesystem. When a
Documentation/filesystems/vfs.rst-96-request is made to mount a filesystem onto a directory in your
--
Documentation/filesystems/vfs.rst=102=file /proc/filesystems.
--
Documentation/filesystems/vfs.rst-104-
Documentation/filesystems/vfs.rst:105:struct file_system_type
Documentation/filesystems/vfs.rst-106------------------------
--
Documentation/filesystems/vfs.rst=109=members are defined:
--
Documentation/filesystems/vfs.rst-112-
Documentation/filesystems/vfs.rst:113: struct file_system_type {
Documentation/filesystems/vfs.rst-114- const char *name;
--
Documentation/filesystems/vfs.rst-119- struct module *owner;
Documentation/filesystems/vfs.rst:120: struct file_system_type * next;
Documentation/filesystems/vfs.rst-121- struct hlist_head fs_supers;
--
arch/powerpc/platforms/cell/spufs/inode.c=508=static int spufs_create_gang(struct inode *inode,
--
arch/powerpc/platforms/cell/spufs/inode.c-524-
arch/powerpc/platforms/cell/spufs/inode.c:525:static struct file_system_type spufs_type;
arch/powerpc/platforms/cell/spufs/inode.c-526-
--
arch/powerpc/platforms/cell/spufs/inode.c=725=static int spufs_init_fs_context(struct fs_context *fc)
--
arch/powerpc/platforms/cell/spufs/inode.c-752-
arch/powerpc/platforms/cell/spufs/inode.c:753:static struct file_system_type spufs_type = {
arch/powerpc/platforms/cell/spufs/inode.c-754- .owner = THIS_MODULE,
--
arch/s390/hypfs/inode.c=43=static const struct file_operations hypfs_file_ops;
arch/s390/hypfs/inode.c:44:static struct file_system_type hypfs_type;
arch/s390/hypfs/inode.c-45-static const struct super_operations hypfs_s_ops;
--
arch/s390/hypfs/inode.c=413=static const struct file_operations hypfs_file_ops = {
--
arch/s390/hypfs/inode.c-419-
arch/s390/hypfs/inode.c:420:static struct file_system_type hypfs_type = {
arch/s390/hypfs/inode.c-421- .owner = THIS_MODULE,
--
arch/um/drivers/mconsole_kern.c=694=static int __init mount_proc(void)
arch/um/drivers/mconsole_kern.c-695-{
arch/um/drivers/mconsole_kern.c:696: struct file_system_type *proc_fs_type;
arch/um/drivers/mconsole_kern.c-697- struct vfsmount *mnt;
--
block/bdev.c=435=static int bd_init_fs_context(struct fs_context *fc)
--
block/bdev.c-444-
block/bdev.c:445:static struct file_system_type bd_type = {
block/bdev.c-446- .name = "bdev",
--
drivers/android/binder/rust_binderfs.c=737=static void binderfs_kill_super(struct super_block *sb)
--
drivers/android/binder/rust_binderfs.c-752-
drivers/android/binder/rust_binderfs.c:753:static struct file_system_type binder_fs_type = {
drivers/android/binder/rust_binderfs.c-754- .name = "binder",
--
drivers/android/binderfs.c=733=static void binderfs_kill_super(struct super_block *sb)
--
drivers/android/binderfs.c-748-
drivers/android/binderfs.c:749:static struct file_system_type binder_fs_type = {
drivers/android/binderfs.c-750- .name = "binder",
--
drivers/base/devtmpfs.c=63=static struct vfsmount *mnt;
drivers/base/devtmpfs.c-64-
drivers/base/devtmpfs.c:65:static struct file_system_type internal_fs_type = {
drivers/base/devtmpfs.c-66- .name = "devtmpfs",
--
drivers/base/devtmpfs.c=90=static int devtmpfs_init_fs_context(struct fs_context *fc)
--
drivers/base/devtmpfs.c-105-
drivers/base/devtmpfs.c:106:static struct file_system_type dev_fs_type = {
drivers/base/devtmpfs.c-107- .name = "devtmpfs",
--
drivers/dax/super.c=394=static int dax_init_fs_context(struct fs_context *fc)
--
drivers/dax/super.c-402-
drivers/dax/super.c:403:static struct file_system_type dax_fs_type = {
drivers/dax/super.c-404- .name = "dax",
--
drivers/dma-buf/dma-buf.c=211=static int dma_buf_fs_init_context(struct fs_context *fc)
--
drivers/dma-buf/dma-buf.c-221-
drivers/dma-buf/dma-buf.c:222:static struct file_system_type dma_buf_fs_type = {
drivers/dma-buf/dma-buf.c-223- .name = "dmabuf",
--
drivers/gpu/drm/drm_drv.c=623=static int drm_fs_init_fs_context(struct fs_context *fc)
--
drivers/gpu/drm/drm_drv.c-627-
drivers/gpu/drm/drm_drv.c:628:static struct file_system_type drm_fs_type = {
drivers/gpu/drm/drm_drv.c-629- .name = "drm",
--
drivers/gpu/drm/drm_gem.c=112=int drm_gem_huge_mnt_create(struct drm_device *dev, const char *value)
drivers/gpu/drm/drm_gem.c-113-{
drivers/gpu/drm/drm_gem.c:114: struct file_system_type *type;
drivers/gpu/drm/drm_gem.c-115- struct fs_context *fc;
--
drivers/misc/ibmasm/ibmasmfs.c=95=static const struct super_operations ibmasmfs_s_ops = {
--
drivers/misc/ibmasm/ibmasmfs.c-99-
drivers/misc/ibmasm/ibmasmfs.c:100:static struct file_system_type ibmasmfs_type = {
drivers/misc/ibmasm/ibmasmfs.c-101- .owner = THIS_MODULE,
--
drivers/usb/gadget/function/f_fs.c=2086=ffs_fs_kill_sb(struct super_block *sb)
--
drivers/usb/gadget/function/f_fs.c-2099-
drivers/usb/gadget/function/f_fs.c:2100:static struct file_system_type ffs_fs_type = {
drivers/usb/gadget/function/f_fs.c-2101- .owner = THIS_MODULE,
--
drivers/usb/gadget/legacy/inode.c=2099=gadgetfs_kill_sb (struct super_block *sb)
--
drivers/usb/gadget/legacy/inode.c-2113-
drivers/usb/gadget/legacy/inode.c:2114:static struct file_system_type gadgetfs_type = {
drivers/usb/gadget/legacy/inode.c-2115- .owner = THIS_MODULE,
--
drivers/vfio/vfio_main.c=242=static int vfio_fs_init_fs_context(struct fs_context *fc)
--
drivers/vfio/vfio_main.c-246-
drivers/vfio/vfio_main.c:247:static struct file_system_type vfio_fs_type = {
drivers/vfio/vfio_main.c-248- .name = "vfio",
--
drivers/xen/xenfs/super.c=81=static int xenfs_init_fs_context(struct fs_context *fc)
--
drivers/xen/xenfs/super.c-86-
drivers/xen/xenfs/super.c:87:static struct file_system_type xenfs_type = {
drivers/xen/xenfs/super.c-88- .owner = THIS_MODULE,
--
fs/9p/v9fs_vfs.h-30-
fs/9p/v9fs_vfs.h:31:extern struct file_system_type v9fs_fs_type;
fs/9p/v9fs_vfs.h-32-extern const struct address_space_operations v9fs_addr_operations;
--
fs/9p/vfs_super.c=307=static int v9fs_init_fs_context(struct fs_context *fc)
--
fs/9p/vfs_super.c-356-
fs/9p/vfs_super.c:357:struct file_system_type v9fs_fs_type = {
fs/9p/vfs_super.c-358- .name = "9p",
--
fs/adfs/super.c=436=static int adfs_init_fs_context(struct fs_context *fc)
--
fs/adfs/super.c-464-
fs/adfs/super.c:465:static struct file_system_type adfs_fs_type = {
fs/adfs/super.c-466- .owner = THIS_MODULE,
--
fs/affs/super.c=614=static int affs_init_fs_context(struct fs_context *fc)
--
fs/affs/super.c-646-
fs/affs/super.c:647:static struct file_system_type affs_fs_type = {
fs/affs/super.c-648- .owner = THIS_MODULE,
--
fs/afs/internal.h=257=static inline struct afs_super_info *AFS_FS_S(struct super_block *sb)
--
fs/afs/internal.h-261-
fs/afs/internal.h:262:extern struct file_system_type afs_fs_type;
fs/afs/internal.h-263-
--
fs/afs/super.c=41=static const struct fs_parameter_spec afs_fs_parameters[];
fs/afs/super.c-42-
fs/afs/super.c:43:struct file_system_type afs_fs_type = {
fs/afs/super.c-44- .owner = THIS_MODULE,
--
fs/aio.c=290=static int __init aio_setup(void)
fs/aio.c-291-{
fs/aio.c:292: static struct file_system_type aio_fs = {
fs/aio.c-293- .name = "aio",
--
fs/anon_inodes.c=84=static int anon_inodefs_init_fs_context(struct fs_context *fc)
--
fs/anon_inodes.c-94-
fs/anon_inodes.c:95:static struct file_system_type anon_inode_fs_type = {
fs/anon_inodes.c-96- .name = "anon_inodefs",
--
fs/autofs/autofs_i.h-47-
fs/autofs/autofs_i.h:48:extern struct file_system_type autofs_fs_type;
fs/autofs/autofs_i.h-49-
--
fs/autofs/init.c-9-
fs/autofs/init.c:10:struct file_system_type autofs_fs_type = {
fs/autofs/init.c-11- .owner = THIS_MODULE,
--
fs/befs/linuxvfs.c=973=static void befs_free_fc(struct fs_context *fc)
--
fs/befs/linuxvfs.c-980-
fs/befs/linuxvfs.c:981:static struct file_system_type befs_fs_type = {
fs/befs/linuxvfs.c-982- .owner = THIS_MODULE,
--
fs/bfs/inode.c=477=static int bfs_init_fs_context(struct fs_context *fc)
--
fs/bfs/inode.c-483-
fs/bfs/inode.c:484:static struct file_system_type bfs_fs_type = {
fs/bfs/inode.c-485- .owner = THIS_MODULE,
--
fs/binfmt_misc.c=50=typedef struct {
--
fs/binfmt_misc.c-63-
fs/binfmt_misc.c:64:static struct file_system_type bm_fs_type;
fs/binfmt_misc.c-65-
--
fs/binfmt_misc.c=1016=static struct linux_binfmt misc_format = {
--
fs/binfmt_misc.c-1020-
fs/binfmt_misc.c:1021:static struct file_system_type bm_fs_type = {
fs/binfmt_misc.c-1022- .owner = THIS_MODULE,
--
fs/btrfs/super.c=66=static const struct super_operations btrfs_super_ops;
fs/btrfs/super.c:67:static struct file_system_type btrfs_fs_type;
fs/btrfs/super.c-68-
--
fs/btrfs/super.c=2172=static int btrfs_init_fs_context(struct fs_context *fc)
--
fs/btrfs/super.c-2200-
fs/btrfs/super.c:2201:static struct file_system_type btrfs_fs_type = {
fs/btrfs/super.c-2202- .owner = THIS_MODULE,
--
fs/btrfs/tests/btrfs-tests.c=42=static int btrfs_test_init_fs_context(struct fs_context *fc)
--
fs/btrfs/tests/btrfs-tests.c-50-
fs/btrfs/tests/btrfs-tests.c:51:static struct file_system_type test_type = {
fs/btrfs/tests/btrfs-tests.c-52- .name = "btrfs_test_fs",
--
fs/ceph/super.c=1527=static void ceph_kill_sb(struct super_block *s)
--
fs/ceph/super.c-1591-
fs/ceph/super.c:1592:static struct file_system_type ceph_fs_type = {
fs/ceph/super.c-1593- .owner = THIS_MODULE,
--
fs/coda/coda_int.h=6=struct file;
fs/coda/coda_int.h-7-
fs/coda/coda_int.h:8:extern struct file_system_type coda_fs_type;
fs/coda/coda_int.h-9-extern unsigned long coda_timeout;
--
fs/coda/inode.c=380=static int coda_init_fs_context(struct fs_context *fc)
--
fs/coda/inode.c-392-
fs/coda/inode.c:393:struct file_system_type coda_fs_type = {
fs/coda/inode.c-394- .owner = THIS_MODULE,
--
fs/configfs/mount.c=109=static int configfs_init_fs_context(struct fs_context *fc)
--
fs/configfs/mount.c-114-
fs/configfs/mount.c:115:static struct file_system_type configfs_fs_type = {
fs/configfs/mount.c-116- .owner = THIS_MODULE,
--
fs/cramfs/inode.c=975=static int cramfs_init_fs_context(struct fs_context *fc)
--
fs/cramfs/inode.c-980-
fs/cramfs/inode.c:981:static struct file_system_type cramfs_fs_type = {
fs/cramfs/inode.c-982- .owner = THIS_MODULE,
--
fs/debugfs/inode.c=309=static int debugfs_init_fs_context(struct fs_context *fc)
--
fs/debugfs/inode.c-323-
fs/debugfs/inode.c:324:static struct file_system_type debug_fs_type = {
fs/debugfs/inode.c-325- .owner = THIS_MODULE,
--
fs/devpts/inode.c=443=static void devpts_kill_sb(struct super_block *sb)
--
fs/devpts/inode.c-452-
fs/devpts/inode.c:453:static struct file_system_type devpts_fs_type = {
fs/devpts/inode.c-454- .name = "devpts",
--
fs/ecryptfs/main.c=428=struct kmem_cache *ecryptfs_sb_info_cache;
fs/ecryptfs/main.c:429:static struct file_system_type ecryptfs_fs_type;
fs/ecryptfs/main.c-430-
--
fs/ecryptfs/main.c=608=static int ecryptfs_init_fs_context(struct fs_context *fc)
--
fs/ecryptfs/main.c-630-
fs/ecryptfs/main.c:631:static struct file_system_type ecryptfs_fs_type = {
fs/ecryptfs/main.c-632- .owner = THIS_MODULE,
--
fs/efivarfs/super.c=410=static int efivarfs_check_missing(efi_char16_t *name16, efi_guid_t vendor,
--
fs/efivarfs/super.c-445-
fs/efivarfs/super.c:446:static struct file_system_type efivarfs_type;
fs/efivarfs/super.c-447-
--
fs/efivarfs/super.c=521=static void efivarfs_kill_sb(struct super_block *sb)
--
fs/efivarfs/super.c-530-
fs/efivarfs/super.c:531:static struct file_system_type efivarfs_type = {
fs/efivarfs/super.c-532- .owner = THIS_MODULE,
--
fs/efs/super.c=32=static struct pt_types sgi_pt_types[] = {
--
fs/efs/super.c-53- */
fs/efs/super.c:54:static struct file_system_type efs_fs_type = {
fs/efs/super.c-55- .owner = THIS_MODULE,
--
fs/erofs/internal.h=185=static inline bool erofs_is_fileio_mode(struct erofs_sb_info *sbi)
--
fs/erofs/internal.h-189-
fs/erofs/internal.h:190:extern struct file_system_type erofs_anon_fs_type;
fs/erofs/internal.h-191-
--
fs/erofs/super.c=952=static void erofs_put_super(struct super_block *sb)
--
fs/erofs/super.c-964-
fs/erofs/super.c:965:static struct file_system_type erofs_fs_type = {
fs/erofs/super.c-966- .owner = THIS_MODULE,
--
fs/erofs/super.c=991=static int erofs_anon_init_fs_context(struct fs_context *fc)
--
fs/erofs/super.c-1001-
fs/erofs/super.c:1002:struct file_system_type erofs_anon_fs_type = {
fs/erofs/super.c-1003- .name = "pseudo_erofs",
--
fs/exfat/super.c=860=static void exfat_kill_sb(struct super_block *sb)
--
fs/exfat/super.c-868-
fs/exfat/super.c:869:static struct file_system_type exfat_fs_type = {
fs/exfat/super.c-870- .owner = THIS_MODULE,
--
fs/ext2/super.c=1669=static int ext2_init_fs_context(struct fs_context *fc)
--
fs/ext2/super.c-1697-
fs/ext2/super.c:1698:static struct file_system_type ext2_fs_type = {
fs/ext2/super.c-1699- .owner = THIS_MODULE,
--
fs/ext4/extents-test.c=133=static int ext_set(struct super_block *sb, void *data)
--
fs/ext4/extents-test.c-137-
fs/ext4/extents-test.c:138:static struct file_system_type ext_fs_type = {
fs/ext4/extents-test.c-139- .name = "extents test",
--
fs/ext4/mballoc-test.c=60=static void mbt_kill_sb(struct super_block *sb)
--
fs/ext4/mballoc-test.c-64-
fs/ext4/mballoc-test.c:65:static struct file_system_type mbt_fs_type = {
fs/ext4/mballoc-test.c-66- .name = "mballoc test",
--
fs/ext4/super.c=125=static const struct fs_context_operations ext4_context_ops = {
--
fs/ext4/super.c-133-#if !defined(CONFIG_EXT2_FS) && !defined(CONFIG_EXT2_FS_MODULE) && defined(CONFIG_EXT4_USE_FOR_EXT2)
fs/ext4/super.c:134:static struct file_system_type ext2_fs_type = {
fs/ext4/super.c-135- .owner = THIS_MODULE,
--
fs/ext4/super.c=143=MODULE_ALIAS("ext2");
--
fs/ext4/super.c-149-
fs/ext4/super.c:150:static struct file_system_type ext3_fs_type = {
fs/ext4/super.c-151- .owner = THIS_MODULE,
--
fs/ext4/super.c=7456=static void ext4_kill_sb(struct super_block *sb)
--
fs/ext4/super.c-7466-
fs/ext4/super.c:7467:static struct file_system_type ext4_fs_type = {
fs/ext4/super.c-7468- .owner = THIS_MODULE,
--
fs/f2fs/super.c=5508=static int f2fs_init_fs_context(struct fs_context *fc)
--
fs/f2fs/super.c-5521-
fs/f2fs/super.c:5522:static struct file_system_type f2fs_fs_type = {
fs/f2fs/super.c-5523- .owner = THIS_MODULE,
--
fs/fat/namei_msdos.c=677=static int msdos_init_fs_context(struct fs_context *fc)
--
fs/fat/namei_msdos.c-689-
fs/fat/namei_msdos.c:690:static struct file_system_type msdos_fs_type = {
fs/fat/namei_msdos.c-691- .owner = THIS_MODULE,
--
fs/fat/namei_vfat.c=1222=static int vfat_init_fs_context(struct fs_context *fc)
--
fs/fat/namei_vfat.c-1234-
fs/fat/namei_vfat.c:1235:static struct file_system_type vfat_fs_type = {
fs/fat/namei_vfat.c-1236- .owner = THIS_MODULE,
--
fs/filesystems.c-33-
fs/filesystems.c:34:static struct file_system_type *file_systems;
fs/filesystems.c-35-static DEFINE_RWLOCK(file_systems_lock);
--
fs/filesystems.c-37-/* WARNING: This can be used only if we _already_ own a reference */
fs/filesystems.c:38:struct file_system_type *get_filesystem(struct file_system_type *fs)
fs/filesystems.c-39-{
--
fs/filesystems.c-43-
fs/filesystems.c:44:void put_filesystem(struct file_system_type *fs)
fs/filesystems.c-45-{
--
fs/filesystems.c-48-
fs/filesystems.c:49:static struct file_system_type **find_filesystem(const char *name, unsigned len)
fs/filesystems.c-50-{
fs/filesystems.c:51: struct file_system_type **p;
fs/filesystems.c-52- for (p = &file_systems; *p; p = &(*p)->next)
--
fs/filesystems.c-66- *
fs/filesystems.c:67: * The &struct file_system_type that is passed is linked into the kernel
fs/filesystems.c-68- * structures and must not be freed until the file system has been
--
fs/filesystems.c-71-
fs/filesystems.c:72:int register_filesystem(struct file_system_type * fs)
fs/filesystems.c-73-{
fs/filesystems.c-74- int res = 0;
fs/filesystems.c:75: struct file_system_type ** p;
fs/filesystems.c-76-
--
fs/filesystems.c=94=EXPORT_SYMBOL(register_filesystem);
--
fs/filesystems.c-103- *
fs/filesystems.c:104: * Once this function has returned the &struct file_system_type structure
fs/filesystems.c-105- * may be freed or reused.
--
fs/filesystems.c-107-
fs/filesystems.c:108:int unregister_filesystem(struct file_system_type * fs)
fs/filesystems.c-109-{
fs/filesystems.c:110: struct file_system_type ** tmp;
fs/filesystems.c-111-
--
fs/filesystems.c=132=static int fs_index(const char __user * __name)
fs/filesystems.c-133-{
fs/filesystems.c:134: struct file_system_type * tmp;
fs/filesystems.c-135- char *name __free(kfree) = strndup_user(__name, PATH_MAX);
--
fs/filesystems.c=153=static int fs_name(unsigned int index, char __user * buf)
fs/filesystems.c-154-{
fs/filesystems.c:155: struct file_system_type * tmp;
fs/filesystems.c-156- int len, res = -EINVAL;
]
]
|
| 34/2 |
2026/05/17 01:32 |
llm |
expert |
0m
Model:
Tokens:
input: 62464
output: 24
thoughts: 23
Thoughts: Okay, here's my summary, taking the perspective of someone familiar with kernel file system code:
**Diving into the NTFS3 Superblock**
Alright, time to get down to brass tacks. I need to understand how the NTFS3 file system type is defined within the kernel. My immediate thought is to go straight to the source. Specifically, I need to check out `fs/ntfs3/super.c`. That's where I expect to find the core definitions related to the file system's superblock data structures and, consequently, the `file_system_type` structure associated with NTFS3. It's the logical place to start digging for the crucial details I need. Let's see what's what.
|
| 35/2 |
2026/05/17 01:32 |
tool |
grepper |
0m
Error:
Args: map[Expression:struct file_system_type.*ntfs3]
Results:
|
| 36/2 |
2026/05/17 01:32 |
llm |
expert |
0m
Model:
Tokens:
input: 62679
output: 21
thoughts: 25
Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience:
**Diving into the NTFS3 Filesystem Superblock**
Alright, so we're talking `ntfs3`. My initial instinct is to dig straight into the superblock handling. Specifically, I'm thinking about the definition of `ntfs3_fs_type`. That's where the filesystem's identity and key characteristics are declared, and I need to confirm its parameters. The logical place to start that analysis is usually the core filesystem-specific code and in this case that points to the likely location: `fs/ntfs3/super.c`. That file is where I expect to find the type definition and potentially the initialization and registration of the NTFS3 filesystem. I need to refresh my memory on the struct and confirm how it interacts with the kernel's virtual filesystem (VFS) layer. I'm after the fundamental pieces that glue it all together.
|
| 37/2 |
2026/05/17 01:32 |
tool |
grepper |
0m
Error:
Args: map[Expression:ntfs3_fs_type]
Results:
|
| 38/2 |
2026/05/17 01:32 |
llm |
expert |
0m
Model:
Tokens:
input: 62937
output: 20
thoughts: 24
Thoughts: Here's my thought process, as if I were considering this code:
**Diving into NTFS3 Superblock Handling**
Okay, so I need to understand how the kernel recognizes and interacts with the NTFS3 filesystem, particularly how it's identified. The first place to check, and likely the most critical, is `fs/ntfs3/super.c`. That's where the core filesystem-specific superblock operations should reside. Specifically, I'm going straight for the `ntfs_fs_type` structure or any relevant function related to filesystem type detection. This should define the filesystem type identifier that the kernel uses to mount and interact with NTFS3 partitions. I want to see how this type is declared, registered, and used by the kernel's VFS layer. This is the entry point for understanding how the kernel knows, "Hey, this is NTFS3!" and then calls the relevant NTFS3 specific code.
|
| 39/2 |
2026/05/17 01:32 |
tool |
grepper |
0m
Args: map[Expression:ntfs_fs_type]
Results: map[Output:fs/ntfs3/super.c=1885=static void ntfs3_kill_sb(struct super_block *sb)
--
fs/ntfs3/super.c-1896-// clang-format off
fs/ntfs3/super.c:1897:static struct file_system_type ntfs_fs_type = {
fs/ntfs3/super.c-1898- .owner = THIS_MODULE,
--
fs/ntfs3/super.c=1949=static int __init init_ntfs_fs(void)
--
fs/ntfs3/super.c-1975- register_as_ntfs_legacy();
fs/ntfs3/super.c:1976: err = register_filesystem(&ntfs_fs_type);
fs/ntfs3/super.c-1977- if (err)
--
fs/ntfs3/super.c=1990=static void __exit exit_ntfs_fs(void)
--
fs/ntfs3/super.c-1993- kmem_cache_destroy(ntfs_inode_cachep);
fs/ntfs3/super.c:1994: unregister_filesystem(&ntfs_fs_type);
fs/ntfs3/super.c-1995- unregister_as_ntfs_legacy();
]
|
| 40/2 |
2026/05/17 01:32 |
llm |
expert |
1m
Model:
Tokens:
input: 63526
output: 44
thoughts: 14
Thoughts: Okay, let's dive into this. Here's my thought process on encountering that piece of text, framed as a first-person summary for an expert like yourself:
**Inspecting the `ntfs_fs_type` Definition**
Alright, so the prompt mentions `ntfs_fs_type`. My initial reaction is a quick mental scan. I immediately assume we're talking about a structure or definition related to the NTFS file system, probably within a kernel context or a low-level library. My brain instantly starts pulling up the typical characteristics of such a definition. Iβm thinking about the likely fields: a superblock, inode information, allocation units, volume descriptors, and potentially function pointers for file system operations like mounting, unmounting, reading, writing, and so on.
I'm starting to anticipate what kind of data structures might be involved. Iβm curious about whether it's a C struct, a class with members, or some other data representation depending on the coding language. I will need to understand what it contains. Is there a `vfs_fs_type` member, or a `super_block`? I wonder if thereβs information about the volume itself.
Now, my mind shifts to context. Whatβs the codebase? Is this Linux, Windows, FreeBSD, or something else entirely? The environment will heavily influence the specific members, naming conventions, and overall structure. I start considering likely sources or API documents where this definition would reside, probably looking at `fs/ntfs/` or similar in a kernel-like structure. My aim is to quickly assess its purpose and how it fits into the broader picture of the file system's implementation. I can start making an informed guess regarding the design choices.
|
| 41/2 |
2026/05/17 01:33 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:fs/ntfs3/super.c IncludeLines:true Name:ntfs_fs_type]
Results: map[SourceCode:1896: // clang-format off
1897: static struct file_system_type ntfs_fs_type = {
1898: .owner = THIS_MODULE,
1899: .name = "ntfs3",
1900: .init_fs_context = ntfs_init_fs_context,
1901: .parameters = ntfs_fs_parameters,
1902: .kill_sb = ntfs3_kill_sb,
1903: .fs_flags = FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
1904: };
SourceFile:fs/ntfs3/super.c]
|
| 42/2 |
2026/05/17 01:33 |
llm |
expert |
0m
Model:
Tokens:
input: 64142
output: 66
thoughts: 2810
Thoughts: **Analysis of the NTFS Vulnerability Report**
Okay, here's the breakdown. This issue revolves around the `ntfs_iomap_begin` function and the potential for an uninitialized value, specifically the `lcn` (logical cluster number), to be used. The core of the problem stems from a scenario where `run_lookup_entry` fails to find a valid cluster mapping, and the `new` flag isn't set, leading to `*len` being zero and `*lcn` remaining uninitialized.
However, after diving deep, this appears to be a classic benign uninitialized value use case. The code paths lead to a controlled error return in all scenarios. Critically, there's no memory corruption, information leak, or denial-of-service vulnerability. While KMSAN (Kernel Memory Sanitizer) might flag the uninitialized value, in a production kernel, KMSAN isn't enabled, so the code would simply return an error. Specifically:
* The code checks `clen`, which is derived from `*len`.
* If `clen` is 0 (because `*len` is 0, which happens if `run_lookup_entry` returns false and `new` isn't set), the function always returns `-EINVAL`.
* Even if `lcn` is `EOF_LCN` or `RESIDENT_LCN`, errors are returned, either `-ENOENT` or `-EFAULT`, depending on flags.
* The `offset` value is always greater than or equal to zero.
* The `lcn` value is not used to access any memory and is not leaked to userspace.
Therefore, it's essentially a no-op that results in a mount failure or read failure.
From a trigger perspective:
* **Peripheral Trigger:** True (a malicious filesystem image on a USB drive can trigger the function).
* **Malicious Filesystem Trigger:** True
* **Exploitable:** False (benign error)
* **Denial of Service:** False (error, does not crash)
* **Accessible From Unprivileged Processes:** False (requires `CAP_SYS_ADMIN`)
* **Accessible From User Namespaces:** False (requires `CAP_SYS_ADMIN` in the initial namespace)
* **VM Guest Trigger:** False
* **VM Host Trigger:** False
* **Ethernet Network Trigger:** False
* **Other Remote Trigger:** False
The bottom line is that while there's a KMSAN report, this is a very low-impact issue, mainly resulting in mount or read failures. It's safe to classify it as a harmless uninitialized variable use.
|
| 43/2 |
2026/05/17 01:34 |
tool |
set-results |
0m
Args: map[DenialOfService:false Exploitable:false FilesystemTrigger:true NetworkTrigger:false PeripheralTrigger:true RemoteTrigger:false Unprivileged:false UserNamespace:false VMGuestTrigger:false VMHostTrigger:false]
Results: map[DenialOfService:false Exploitable:false FilesystemTrigger:true NetworkTrigger:false PeripheralTrigger:true RemoteTrigger:false Unprivileged:false UserNamespace:false VMGuestTrigger:false VMHostTrigger:false]
|
| 44/2 |
2026/05/17 01:34 |
llm |
expert |
0m
Model:
Tokens:
input: 67657
output: 753
thoughts: 314
Thoughts: **My Analysis of the NTFS Driver Vulnerability**
Okay, the analysis is complete, and it's time to craft the final response. Here's what I've concluded. The root cause is that `attr_data_get_block` can return 0, with `*len` set to 0 and `*lcn` uninitialized. This happens when `run_lookup_entry` fails to locate the run, and `new` is null. The subsequent call to `ntfs_iomap_begin` then utilizes this uninitialized `lcn`.
However, the crucial point is that because `clen` (which, remember, *is* `*len`) is zero, `ntfs_iomap_begin` will inevitably return an error, either `-EINVAL` or `-EFAULT`, regardless of the garbage value in `lcn`. The uninitialized value isn't actually *used* in any memory access, pointer arithmetic, or exposed to user space. It just leads to a read operation failure, which is actually the expected outcome when the filesystem is corrupt, and so is benign in its effects. This is, in essence, a KMSAN-caught instance of using an uninitialized value, but it is not exploitable. It doesn't present a denial-of-service risk, either.
The bug's trigger is mounting a malicious NTFS filesystem image. Now, a key factor here is that `ntfs3` doesn't have the `FS_USERNS_MOUNT` flag. Thus, mounting can't be done from a user namespace. The mount requires `CAP_SYS_ADMIN` privileges within the initial user namespace. This makes the vulnerability inaccessible to unprivileged processes or user namespaces. The only way to trigger this is via a peripheral device if the system is configured to auto-mount USB drives.
|
| 45/1 |
2026/05/17 01:34 |
action |
format-explanation |
0m
Results: map[Explanation:Based on the analysis of the source code and the KMSAN report, here is the
assessment of the bug:
**Root Cause Analysis:**
The bug is a KMSAN uninitialized value report in `ntfs_iomap_begin`.
The uninitialized value is the local variable `lcn`, which is passed by
reference to `attr_data_get_block()`.
Inside `attr_data_get_block()`, if the requested virtual cluster number (`vcn`)
is not found in the run list (`run_lookup_entry` returns false) and the caller
did not request allocation of new clusters (`new == NULL`), the function sets
`*len = 0` and jumps to the `ok` label, returning `0` (success) without ever
initializing `*lcn`.
Back in `ntfs_iomap_begin()`, the uninitialized `lcn` is then used in a series
of comparisons:
```c
if (lcn == EOF_LCN) { ... }
...
if (lcn == RESIDENT_LCN) {
if (offset >= clen) { ... return -EFAULT; }
...
}
if (!clen) {
return -EINVAL;
}
```
**Security Impact:**
Although `lcn` is uninitialized, the variable `clen` (which corresponds to
`*len` set by `attr_data_get_block`) is guaranteed to be `0` in this specific
code path.
Because `clen` is `0`, the function will always end up returning an error:
- If `lcn` happens to match `RESIDENT_LCN`, it checks `offset >= clen`. Since
`offset` is a file offset (always `>= 0`) and `clen` is `0`, this condition is
always true, and the function returns `-EFAULT`.
- If `lcn` is anything else (or if it was `EOF_LCN` and got reassigned to
`SPARSE_LCN`), the code eventually reaches `if (!clen)`, which evaluates to
true, and returns `-EINVAL`.
In all cases, the uninitialized value does not influence the control flow in any
dangerous way. It is not used for memory accesses, pointer arithmetic, or leaked
to userspace. It simply results in a read error (`-EINVAL` or `-EFAULT`), which
gracefully propagates up the call stack and fails the operation (e.g., failing
the mount process).
Therefore, this is a **benign** uninitialized value use. It is **not
exploitable** and does **not cause a Denial of Service** (the kernel does not
crash or hang; it just rejects the corrupted filesystem).
**Reachability:**
The bug can be triggered by mounting a maliciously crafted NTFS filesystem image
where the run list does not cover the allocated size of a file.
However, the `ntfs3` filesystem does not have the `FS_USERNS_MOUNT` flag set in
its `file_system_type` definition. This means it cannot be mounted from within a
user namespace. Mounting it requires `CAP_SYS_ADMIN` in the initial user
namespace.
Thus, the bug is **not accessible from unprivileged processes** or **user
namespaces**. It can only be triggered if the root user explicitly mounts the
image, or if the system is configured to auto-mount external media (e.g., USB
drives on a Desktop environment), making it a **Peripheral / Malicious
Filesystem Trigger**.]
|