KASAN: slab-use-after-free Read in v4l2_release (3)

Status: upstream: reported C repro on 2026/09/11 16:15
Subsystems: media
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+34957180b0ed2581edaf@syzkaller.appspotmail.com
First crash: 50d, last: 1d15h
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
4b08af9a repro-c Reproduced: ✅ ❓ KASAN: slab-use-after-free Read in v4l2_release (3) 2026/09/11 12:01 2026/09/11 12:01 2026/09/11 13:41 1fe56c0a
aeb76778 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Read in v4l2_release (3) 2026/09/09 01:45 2026/09/09 01:45 2026/09/09 02:32 243b72f1
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[PATCH] Input: sur40 - fix use-after-free in v4l2_release on disconnect 3 (3) 2026/10/18 10:53
[syzbot] [media?] KASAN: slab-use-after-free Read in v4l2_release (3) 0 (5) 2026/09/17 01:26
▶ ▼ 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_release media usb 19 syz, C error inconclusive 1 644d 707d 0/29 auto-obsoleted due to no activity on 2025/07/14 22:25
upstream KASAN: slab-use-after-free Read in v4l2_release (2) media 19 syz, C error error 6 201d 429d 29/29 fixed on 2026/05/21 07:50
upstream KASAN: use-after-free Read in v4l2_release (3) usb media 19 syz, C error error 34 1928d 2484d 0/29 auto-obsoleted due to no activity on 2023/04/15 03:26
▶ ▼ Last patch testing requests (6)
Created Duration User Patch Repo Result
2026/09/26 22:19 13m retest repro upstream no crash job log log
2026/09/17 01:26 14m jchuang26@m.fudan.edu.cn patch upstream OK job log log
2026/09/15 01:38 14m jchuang26@m.fudan.edu.cn patch upstream OK job log log
2026/09/14 11:46 13m jchuang26@m.fudan.edu.cn patch git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 08df884136f1c1197bab2a27814404fd329d9aac OK job log log
2026/09/12 01:03 18m kartikey406@gmail.com patch upstream OK job log log
2026/09/11 16:00 13m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 08df884136f1c1197bab2a27814404fd329d9aac report job log log

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in v4l2_device_release+0x44f/0x480 drivers/media/v4l2-core/v4l2-dev.c:196
Write of size 8 at addr ffff888028118778 by task v4l_id/7393

CPU: 0 UID: 0 PID: 7393 Comm: v4l_id Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x13d/0x4b0 mm/kasan/report.c:482
 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
 v4l2_device_release+0x44f/0x480 drivers/media/v4l2-core/v4l2-dev.c:196
 device_release+0xd2/0x270 drivers/base/core.c:2640
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1f7/0x640 lib/kobject.c:737
 put_device+0x1f/0x30 drivers/base/core.c:3884
 video_put drivers/media/v4l2-core/v4l2-dev.c:173 [inline]
 v4l2_release+0x2da/0x390 drivers/media/v4l2-core/v4l2-dev.c:480
 __fput+0x3fb/0xb50 fs/file_table.c:512
 fput_close_sync+0x118/0x250 fs/file_table.c:618
 filp_close_sync+0x75/0xa0 fs/open.c:1573
 __do_sys_close fs/open.c:1596 [inline]
 __se_sys_close fs/open.c:1583 [inline]
 __x64_sys_close+0x81/0x110 fs/open.c:1583
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f14ea7da407
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:00007ffeae4f4670 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 00007f14ea74e880 RCX: 00007f14ea7da407
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f14ea74e6e8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000013
R13: 00007ffeae4f48a0 R14: 00007f14eaa33000 R15: 000055a84b7474d8
 </TASK>

Allocated by task 6391:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:409 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:426
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x2f8/0x6d0 mm/slub.c:5680
 _kmalloc_noprof include/linux/slab.h:991 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 em28xx_v4l2_init.cold+0x94/0x3a7f drivers/media/usb/em28xx/em28xx-video.c:2751
 em28xx_init_extension+0x13a/0x200 drivers/media/usb/em28xx/em28xx-core.c:1245
 request_module_async+0x1e/0x30 drivers/media/usb/em28xx/em28xx-cards.c:3723
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3495
 process_scheduled_works kernel/workqueue.c:3578 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3659
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 6160:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:264 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:296
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2780 [inline]
 slab_free mm/slub.c:6630 [inline]
 kfree+0x22b/0x6d0 mm/slub.c:6923
 em28xx_free_v4l2+0x7b/0x110 drivers/media/usb/em28xx/em28xx-video.c:2337
 v4l2_device_release drivers/media/v4l2-core/v4l2-device.c:51 [inline]
 kref_put include/linux/kref.h:65 [inline]
 v4l2_device_put+0xa3/0xd0 drivers/media/v4l2-core/v4l2-device.c:56
 em28xx_v4l2_fini.cold+0x267/0x312 drivers/media/usb/em28xx/em28xx-video.c:2465
 em28xx_close_extension+0xd2/0x460 drivers/media/usb/em28xx/em28xx-core.c:1262
 em28xx_usb_disconnect.cold+0x13d/0x253 drivers/media/usb/em28xx/em28xx-cards.c:4489
 usb_unbind_interface+0x1dd/0x9b0 drivers/usb/core/driver.c:460
 device_remove drivers/base/dd.c:618 [inline]
 device_remove+0x12a/0x180 drivers/base/dd.c:610
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
 bus_remove_device+0x2bc/0x560 drivers/base/bus.c:667
 device_del+0x376/0x9b0 drivers/base/core.c:3965
 usb_disable_device+0x367/0x810 drivers/usb/core/message.c:1484
 usb_disconnect+0x2e2/0x9a0 drivers/usb/core/hub.c:2355
 hub_port_connect drivers/usb/core/hub.c:5425 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5725 [inline]
 port_event drivers/usb/core/hub.c:5889 [inline]
 hub_event+0x1bb1/0x4420 drivers/usb/core/hub.c:5971
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3495
 process_scheduled_works kernel/workqueue.c:3578 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3659
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888028118000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 1912 bytes inside of
 freed 8192-byte region [ffff888028118000, ffff88802811a000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x28118
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801d443180 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000020002 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801d443180 dead000000000100 dead000000000122
head: 0000000000000000 0000000000020002 00000000f5000000 0000000000000000
head: 00fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5576, tgid 5576 (rcS), ts 19371824206
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1854
 prep_new_page mm/page_alloc.c:1862 [inline]
 get_page_from_freelist+0x1113/0x35e0 mm/page_alloc.c:3933
 __alloc_frozen_pages_noprof+0x2f6/0x3190 mm/page_alloc.c:5429
 alloc_slab_page mm/slub.c:3384 [inline]
 allocate_slab mm/slub.c:3499 [inline]
 new_slab+0xb1/0x6d0 mm/slub.c:3550
 refill_objects+0xe3/0x410 mm/slub.c:7539
 refill_sheaf mm/slub.c:2917 [inline]
 __pcs_replace_empty_main+0x35e/0x650 mm/slub.c:4811
 alloc_from_pcs mm/slub.c:4887 [inline]
 slab_alloc_node mm/slub.c:5021 [inline]
 __kmalloc_cache_noprof+0x4ef/0x6d0 mm/slub.c:5676
 _kmalloc_noprof include/linux/slab.h:991 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 tomoyo_print_bprm security/tomoyo/audit.c:26 [inline]
 tomoyo_init_log+0xb78/0x1f80 security/tomoyo/audit.c:262
 tomoyo_supervisor+0x506/0x1340 security/tomoyo/common.c:2232
 tomoyo_audit_env_log security/tomoyo/environ.c:37 [inline]
 tomoyo_env_perm+0x191/0x200 security/tomoyo/environ.c:64
 tomoyo_environ security/tomoyo/domain.c:673 [inline]
 tomoyo_find_next_domain+0x13d7/0x2010 security/tomoyo/domain.c:889
 tomoyo_bprm_check_security security/tomoyo/tomoyo.c:102 [inline]
 tomoyo_bprm_check_security+0x12d/0x1d0 security/tomoyo/tomoyo.c:92
 security_bprm_check+0x87/0x1e0 security/security.c:834
 search_binary_handler fs/exec.c:1767 [inline]
 exec_binprm fs/exec.c:1809 [inline]
 bprm_execve fs/exec.c:1865 [inline]
 bprm_execve+0x80b/0x1940 fs/exec.c:1841
 do_execveat_common.isra.0+0x49d/0x580 fs/exec.c:1963
 __do_sys_execve fs/exec.c:2036 [inline]
 __se_sys_execve fs/exec.c:2030 [inline]
 __x64_sys_execve+0x93/0xd0 fs/exec.c:2030
page last free pid 5567 tgid 5567 ts 19222042330 stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 __free_pages_prepare mm/page_alloc.c:1401 [inline]
 __free_frozen_pages+0x7b4/0x1110 mm/page_alloc.c:2952
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:361
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4720 [inline]
 slab_alloc_node mm/slub.c:5033 [inline]
 __do_kmalloc_node mm/slub.c:5530 [inline]
 __kmalloc_noprof+0x2cc/0x840 mm/slub.c:5556
 _kmalloc_noprof include/linux/slab.h:995 [inline]
 tomoyo_realpath_from_path+0xb6/0x690 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x276/0x460 security/tomoyo/file.c:827
 security_inode_getattr+0x116/0x280 security/security.c:1917
 vfs_getattr fs/stat.c:263 [inline]
 vfs_fstat+0x4b/0xe0 fs/stat.c:285
 __do_sys_newfstat+0x8b/0x110 fs/stat.c:555
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888028118600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888028118680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888028118700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff888028118780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888028118800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/26 06:03 upstream 21a7f44fd076 1d9ca40b .config console log report syz / log [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Write in v4l2_release
2026/09/12 21:55 upstream 5225b8eec4c9 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in v4l2_release
2026/09/09 23:52 upstream 50d05c7c76c9 4e8b1cc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 KASAN: slab-use-after-free Read in v4l2_release
2026/09/11 16:14 git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 08df884136f1 4e8b1cc6 .config console log report C ci-qemu-upstream KASAN: slab-use-after-free Read in v4l2_release
2026/09/07 11:55 upstream df2908090cda 5e4626f5 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in v4l2_release
* Struck through repros no longer work on HEAD.