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KASAN: use-after-free Read in dvb_device_open

Status: upstream: reported C repro on 2026/02/07 10:59
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+e90b3d2c21add5ffde1c@syzkaller.appspotmail.com
First crash: 3d04h, last: 1d01h
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2026/02/08 upstream (ToT) e7aa57247700 C [report] KASAN: slab-use-after-free Read in dvb_device_open
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 KASAN: use-after-free Read in dvb_device_open origin:upstream 19 syz 15 20h15m 1d23h 0/3 upstream: reported syz repro on 2026/02/08 16:16
upstream KASAN: slab-use-after-free Read in dvb_device_open media 19 C 1030 42m 416d 0/29 upstream: reported C repro on 2024/12/21 08:54
linux-6.6 KFENCE: use-after-free read in dvb_device_open origin:upstream 19 syz 7 1d13h 1d16h 0/2 upstream: reported syz repro on 2026/02/08 23:24

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in dvb_device_open+0xc6/0x370 drivers/media/dvb-core/dvbdev.c:99
Read of size 8 at addr ffff888029746618 by task syz.0.19/4422

CPU: 0 PID: 4422 Comm: syz.0.19 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:420
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 dvb_device_open+0xc6/0x370 drivers/media/dvb-core/dvbdev.c:99
 chrdev_open+0x5c5/0x6a0 fs/char_dev.c:414
 do_dentry_open+0x7e9/0x10d0 fs/open.c:882
 do_open fs/namei.c:3634 [inline]
 path_openat+0x2635/0x2ee0 fs/namei.c:3791
 do_filp_open+0x1f1/0x430 fs/namei.c:3818
 do_sys_openat2+0x150/0x4b0 fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_openat fs/open.c:1352 [inline]
 __se_sys_openat fs/open.c:1347 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1347
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f592215b78e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007fff377b5ab8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000055555ceb2500 RCX: 00007f592215b78e
RDX: 0000000000000002 RSI: 00007fff377b5b90 RDI: ffffffffffffff9c
RBP: 00007fff377b5b90 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: cccccccccccccccd
R13: 00007f5922415fac R14: 00007f5922415fa0 R15: 00007f5922415fa0
 </TASK>

Allocated by task 1:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 dvb_register_device+0x311/0x2150 drivers/media/dvb-core/dvbdev.c:478
 dvb_register_frontend+0x645/0x920 drivers/media/dvb-core/dvb_frontend.c:3035
 vidtv_bridge_dvb_init drivers/media/test-drivers/vidtv/vidtv_bridge.c:436 [inline]
 vidtv_bridge_probe+0x9a1/0xf70 drivers/media/test-drivers/vidtv/vidtv_bridge.c:508
 platform_probe+0x137/0x1c0 drivers/base/platform.c:1400
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x2aa/0xc70 drivers/base/dd.c:639
 __driver_probe_device+0x18c/0x330 drivers/base/dd.c:785
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:815
 __driver_attach+0x44a/0x6e0 drivers/base/dd.c:1201
 bus_for_each_dev+0x182/0x1f0 drivers/base/bus.c:303
 bus_add_driver+0x30a/0x5a0 drivers/base/bus.c:620
 driver_register+0x32d/0x430 drivers/base/driver.c:246
 vidtv_bridge_init+0x39/0x67 drivers/media/test-drivers/vidtv/vidtv_bridge.c:600
 do_one_initcall+0x26a/0x840 init/main.c:1310
 do_initcall_level+0x137/0x1e4 init/main.c:1383
 do_initcalls+0x4b/0x8a init/main.c:1399
 kernel_init_freeable+0x415/0x5be init/main.c:1638
 kernel_init+0x19/0x1b0 init/main.c:1526
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Freed by task 4421:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xb6/0x1f0 mm/slub.c:3700
 dvb_free_device drivers/media/dvb-core/dvbdev.c:625 [inline]
 kref_put include/linux/kref.h:65 [inline]
 dvb_device_put drivers/media/dvb-core/dvbdev.c:640 [inline]
 dvb_device_open+0x2e7/0x370 drivers/media/dvb-core/dvbdev.c:113
 chrdev_open+0x5c5/0x6a0 fs/char_dev.c:414
 do_dentry_open+0x7e9/0x10d0 fs/open.c:882
 do_open fs/namei.c:3634 [inline]
 path_openat+0x2635/0x2ee0 fs/namei.c:3791
 do_filp_open+0x1f1/0x430 fs/namei.c:3818
 do_sys_openat2+0x150/0x4b0 fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_openat fs/open.c:1352 [inline]
 __se_sys_openat fs/open.c:1347 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1347
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff888029746600
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 24 bytes inside of
 256-byte region [ffff888029746600, ffff888029746700)

The buggy address belongs to the physical page:
page:ffffea0000a5d180 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x29746
head:ffffea0000a5d180 order:1 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888017441b40
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 17986844941, free_ts 0
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2559
 prep_new_page mm/page_alloc.c:2566 [inline]
 get_page_from_freelist+0x1a1e/0x1ab0 mm/page_alloc.c:4357
 __alloc_pages+0x1ec/0x4f0 mm/page_alloc.c:5643
 alloc_page_interleave+0x24/0x1e0 mm/mempolicy.c:2115
 alloc_slab_page+0x5d/0x160 mm/slub.c:1799
 allocate_slab mm/slub.c:1944 [inline]
 new_slab+0x87/0x2c0 mm/slub.c:1997
 ___slab_alloc+0xbc6/0x1240 mm/slub.c:3154
 __slab_alloc mm/slub.c:3240 [inline]
 slab_alloc_node mm/slub.c:3325 [inline]
 __kmem_cache_alloc_node+0x1a0/0x260 mm/slub.c:3398
 kmalloc_trace+0x26/0xe0 mm/slab_common.c:1026
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 bus_add_driver+0xda/0x5a0 drivers/base/bus.c:604
 driver_register+0x32d/0x430 drivers/base/driver.c:246
 i2c_register_driver+0xb6/0x160 drivers/i2c/i2c-core-base.c:2021
 do_one_initcall+0x26a/0x840 init/main.c:1310
 do_initcall_level+0x137/0x1e4 init/main.c:1383
 do_initcalls+0x4b/0x8a init/main.c:1399
 kernel_init_freeable+0x415/0x5be init/main.c:1638
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888029746500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888029746580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888029746600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff888029746680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888029746700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/07 17:35 linux-6.1.y 0182cb5b74ee f20fc9f9 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in dvb_device_open
2026/02/07 10:59 linux-6.1.y 0182cb5b74ee f20fc9f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in dvb_device_open
2026/02/07 10:59 linux-6.1.y 0182cb5b74ee f20fc9f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in dvb_device_open
2026/02/07 10:58 linux-6.1.y 0182cb5b74ee f20fc9f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in dvb_device_open
2026/02/09 14:02 linux-6.1.y 0182cb5b74ee df949cd9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in dvb_device_open
2026/02/07 23:19 linux-6.1.y 0182cb5b74ee 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in dvb_device_open
2026/02/07 13:14 linux-6.1.y 0182cb5b74ee f20fc9f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in dvb_device_open
* Struck through repros no longer work on HEAD.