KASAN: use-after-free Read in v4l2_open

Status: upstream: reported C repro on 2026/06/03 20:38
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+c5ac76891d9b32bfdfad@syzkaller.appspotmail.com
First crash: 50d, last: 2d16h
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2026/06/23 upstream (ToT) f31c00c377cc C [report] KASAN: slab-use-after-free Read in v4l2_open
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Read in v4l2_open prio:high usb media 19 C error 2452 5m 127d 0/29 upstream: reported C repro on 2026/03/19 07:21
linux-5.15 KASAN: use-after-free Read in v4l2_open origin:upstream 19 C 40 4d05h 50d 0/3 upstream: reported C repro on 2026/06/03 16:24
linux-6.6 KASAN: slab-use-after-free Read in v4l2_open origin:upstream 19 C 5 8d05h 71d 0/2 upstream: reported C repro on 2026/05/14 00:02

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in v4l2_open+0x32d/0x340 drivers/media/v4l2-core/v4l2-dev.c:432
Read of size 4 at addr ffff8880766a07e8 by task v4l_id/4524

CPU: 0 PID: 4524 Comm: v4l_id Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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
 v4l2_open+0x32d/0x340 drivers/media/v4l2-core/v4l2-dev.c:432
 chrdev_open+0x585/0x5f0 fs/char_dev.c:414
 do_dentry_open+0x7dd/0x10b0 fs/open.c:882
 do_open fs/namei.c:3634 [inline]
 path_openat+0x2674/0x2f10 fs/namei.c:3791
 do_filp_open+0x1ee/0x420 fs/namei.c:3818
 do_sys_openat2+0x14b/0x4f0 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: 0033:0x7f106c7df407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffd093b3920 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f106c753880 RCX: 00007f106c7df407
RDX: 0000000000000000 RSI: 00007ffd093b4f1c RDI: ffffffffffffff9c
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007ffd093b3b70 R14: 00007f106ca30000 R15: 0000556f24b794d8
 </TASK>

Allocated by task 4436:
 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]
 em28xx_v4l2_init+0xf5/0x2d90 drivers/media/usb/em28xx/em28xx-video.c:2538
 em28xx_init_extension+0x118/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1116
 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Freed by task 4436:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1f0 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+0x133/0x1b0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xb6/0x200 mm/slub.c:3700
 em28xx_free_v4l2 drivers/media/usb/em28xx/em28xx-video.c:2118 [inline]
 kref_put include/linux/kref.h:65 [inline]
 em28xx_v4l2_init+0x15f7/0x2d90 drivers/media/usb/em28xx/em28xx-video.c:2907
 em28xx_init_extension+0x118/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1116
 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff8880766a0000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 2024 bytes inside of
 8192-byte region [ffff8880766a0000, ffff8880766a2000)

The buggy address belongs to the physical page:
page:ffffea0001d9a800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x766a0
head:ffffea0001d9a800 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888017442280
raw: 0000000000000000 0000000080020002 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 4436, tgid 4436 (kworker/1:5), ts 104931525320, free_ts 104911049296
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2560
 prep_new_page mm/page_alloc.c:2567 [inline]
 get_page_from_freelist+0x206b/0x2180 mm/page_alloc.c:4358
 __alloc_pages+0x1ec/0x4f0 mm/page_alloc.c:5658
 alloc_slab_page+0x5d/0x180 mm/slub.c:1799
 allocate_slab mm/slub.c:1944 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:1997
 ___slab_alloc+0xbc5/0x1240 mm/slub.c:3154
 __slab_alloc mm/slub.c:3240 [inline]
 slab_alloc_node mm/slub.c:3325 [inline]
 __kmem_cache_alloc_node+0x126/0x270 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]
 em28xx_v4l2_init+0xf5/0x2d90 drivers/media/usb/em28xx/em28xx-video.c:2538
 em28xx_init_extension+0x118/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1116
 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1487 [inline]
 free_pcp_prepare mm/page_alloc.c:1537 [inline]
 free_unref_page_prepare+0x8e5/0x9e0 mm/page_alloc.c:3414
 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3509
 free_slab mm/slub.c:2036 [inline]
 discard_slab mm/slub.c:2042 [inline]
 __unfreeze_partials+0x188/0x1e0 mm/slub.c:2591
 put_cpu_partial+0x17c/0x250 mm/slub.c:2667
 qlink_free mm/kasan/quarantine.c:168 [inline]
 qlist_free_all+0x76/0xe0 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x144/0x160 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0x1e/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook+0x4b/0x490 mm/slab.h:737
 slab_alloc_node mm/slub.c:3359 [inline]
 slab_alloc mm/slub.c:3367 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3374 [inline]
 kmem_cache_alloc+0x18b/0x2f0 mm/slub.c:3383
 getname_flags+0xb7/0x500 fs/namei.c:139
 vfs_fstatat fs/stat.c:266 [inline]
 __do_sys_newfstatat fs/stat.c:437 [inline]
 __se_sys_newfstatat fs/stat.c:431 [inline]
 __x64_sys_newfstatat+0x16f/0x240 fs/stat.c:431
 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

Memory state around the buggy address:
 ffff8880766a0680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880766a0700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880766a0780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                          ^
 ffff8880766a0800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880766a0880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (18):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/21 23:16 linux-6.1.y fdb6fcb41cc7 43bfcdb0 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/07/21 21:35 linux-6.1.y 090666d3cc90 7c5de9c3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/07/16 09:03 linux-6.1.y 090666d3cc90 27a8bd60 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/07/16 08:16 linux-6.1.y 090666d3cc90 27a8bd60 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/07/15 16:04 linux-6.1.y 090666d3cc90 a4ed0f4f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/07/13 21:35 linux-6.1.y 090666d3cc90 cc4833d0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/07/11 02:14 linux-6.1.y 090666d3cc90 d78ea535 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/07/07 10:48 linux-6.1.y 090666d3cc90 8e71ce95 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/07/06 16:53 linux-6.1.y 090666d3cc90 88b240e4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/07/05 06:30 linux-6.1.y 090666d3cc90 fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/06/30 20:29 linux-6.1.y fdb6fcb41cc7 00e8b0fd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/06/25 12:24 linux-6.1.y fdb6fcb41cc7 cfa969bf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/06/21 22:20 linux-6.1.y fdb6fcb41cc7 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/06/09 23:28 linux-6.1.y 228da13e907e 34dab4be .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/06/08 14:39 linux-6.1.y 228da13e907e 656e94c6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/06/04 07:11 linux-6.1.y 228da13e907e 197909be .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/06/03 20:40 linux-6.1.y 228da13e907e 234057e5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
2026/06/03 20:38 linux-6.1.y 228da13e907e 234057e5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in v4l2_open
* Struck through repros no longer work on HEAD.