Re: [syzbot] [media?] KASAN: slab-use-after-free Read in __vb2_queue_cancel (2)

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    08dbfad3f504 Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11740349580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=19560cab9a915237
dashboard link: https://syzkaller.appspot.com/bug?extid=dd0f06181ab66b93dc00
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10c45d79580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10eeee25580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5896a88f5701/disk-08dbfad3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/af401a4b0127/vmlinux-08dbfad3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c322757c580c/bzImage-08dbfad3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dd0f06181ab66b93dc00@xxxxxxxxxxxxxxxxxxxxxxxxx

 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 UID: 0 PID: 25 Comm: kworker/1:0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026
Workqueue: events request_module_async
RIP: 0010:__wake_up_common+0x9b/0x1f0 kernel/sched/wait.c:105
Code: 02 00 0f 85 5b 01 00 00 48 8b 5b 40 48 8d 43 e8 4c 39 fb 0f 84 b3 00 00 00 48 ba 00 00 00 00 00 fc ff df 48 89 d9 48 c1 e9 03 <80> 3c 11 00 0f 85 18 01 00 00 48 bd 00 00 00 00 00 fc ff df 4c 8b
RSP: 0018:ffffc900001f79a0 EFLAGS: 00010056
RAX: ffffffffffffffe8 RBX: 0000000000000000 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000003 RDI: ffff8880298b5790
RBP: ffff8880298b5790 R08: 0000000000000000 R09: fffff5200003ef2b
R10: 0000000000000003 R11: 00000000000075fb R12: 0000000000000003
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8880298b57d0
FS:  0000000000000000(0000) GS:ffff888123c61000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000557902ace698 CR3: 0000000034273000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 __wake_up_common_lock kernel/sched/wait.c:126 [inline]
 __wake_up+0x31/0x60 kernel/sched/wait.c:147
 __vb2_queue_cancel+0x348/0xe90 drivers/media/common/videobuf2/videobuf2-core.c:2244
 vb2_core_queue_release+0x27/0x190 drivers/media/common/videobuf2/videobuf2-core.c:2677
 vb2_queue_release drivers/media/common/videobuf2/videobuf2-v4l2.c:943 [inline]
 vb2_video_unregister_device drivers/media/common/videobuf2/videobuf2-v4l2.c:1279 [inline]
 vb2_video_unregister_device+0x152/0x2e0 drivers/media/common/videobuf2/videobuf2-v4l2.c:1254
 em28xx_v4l2_init.cold+0xe1a/0x3a18 drivers/media/usb/em28xx/em28xx-video.c:3097
 em28xx_init_extension+0x13a/0x200 drivers/media/usb/em28xx/em28xx-core.c:1248
 request_module_async+0x1e/0x30 drivers/media/usb/em28xx/em28xx-cards.c:3685
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387
 process_scheduled_works kernel/workqueue.c:3470 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551
 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
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__wake_up_common+0x9b/0x1f0 kernel/sched/wait.c:105
Code: 02 00 0f 85 5b 01 00 00 48 8b 5b 40 48 8d 43 e8 4c 39 fb 0f 84 b3 00 00 00 48 ba 00 00 00 00 00 fc ff df 48 89 d9 48 c1 e9 03 <80> 3c 11 00 0f 85 18 01 00 00 48 bd 00 00 00 00 00 fc ff df 4c 8b
RSP: 0018:ffffc900001f79a0 EFLAGS: 00010056
RAX: ffffffffffffffe8 RBX: 0000000000000000 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000003 RDI: ffff8880298b5790
RBP: ffff8880298b5790 R08: 0000000000000000 R09: fffff5200003ef2b
R10: 0000000000000003 R11: 00000000000075fb R12: 0000000000000003
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8880298b57d0
FS:  0000000000000000(0000) GS:ffff888123c61000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000557902ace698 CR3: 0000000034273000 CR4: 0000000000350ef0
----------------
Code disassembly (best guess):
   0:	02 00                	add    (%rax),%al
   2:	0f 85 5b 01 00 00    	jne    0x163
   8:	48 8b 5b 40          	mov    0x40(%rbx),%rbx
   c:	48 8d 43 e8          	lea    -0x18(%rbx),%rax
  10:	4c 39 fb             	cmp    %r15,%rbx
  13:	0f 84 b3 00 00 00    	je     0xcc
  19:	48 ba 00 00 00 00 00 	movabs $0xdffffc0000000000,%rdx
  20:	fc ff df
  23:	48 89 d9             	mov    %rbx,%rcx
  26:	48 c1 e9 03          	shr    $0x3,%rcx
* 2a:	80 3c 11 00          	cmpb   $0x0,(%rcx,%rdx,1) <-- trapping instruction
  2e:	0f 85 18 01 00 00    	jne    0x14c
  34:	48 bd 00 00 00 00 00 	movabs $0xdffffc0000000000,%rbp
  3b:	fc ff df
  3e:	4c                   	rex.WR
  3f:	8b                   	.byte 0x8b


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