syzbot


general protection fault in dvb_dmxdev_filter_stop

Status: moderation: reported on 2026/03/02 22:25
Subsystems: media
[Documentation on labels]
Reported-by: syzbot+74014f72890a415f7401@syzkaller.appspotmail.com
First crash: 21d, last: 21d

Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
CPU: 1 UID: 0 PID: 6999 Comm: syz.0.396 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:dvb_dmxdev_feed_stop drivers/media/dvb-core/dmxdev.c:494 [inline]
RIP: 0010:dvb_dmxdev_filter_stop+0x1a9/0x720 drivers/media/dvb-core/dmxdev.c:572
Code: 00 00 49 8d 5c 24 f8 48 89 d8 48 c1 e8 03 80 3c 28 00 74 08 48 89 df e8 75 f7 47 fa 48 8b 1b 48 8d 7b 28 48 89 f8 48 c1 e8 03 <80> 3c 28 00 74 05 e8 5c f7 47 fa 4c 8b 5b 28 48 89 df 2e e8 db ac
RSP: 0018:ffffc90004327c58 EFLAGS: 00010206
RAX: 0000000000000005 RBX: 0000000000000000 RCX: 0000000000000005
RDX: ffffffff87e8110a RSI: ffffffff8f8e1200 RDI: 0000000000000028
RBP: dffffc0000000000 R08: ffff88803287bd00 R09: 0000000000000002
R10: 0000000000000002 R11: 0000000000000000 R12: ffff888025c1f510
R13: ffffc900064dc540 R14: 1ffff92000c9b8a8 R15: ffffc900064dc4e8
FS:  0000555581367500(0000) GS:ffff88812511b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2df5db CR3: 000000007ef5e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 dvb_dmxdev_filter_free drivers/media/dvb-core/dmxdev.c:856 [inline]
 dvb_demux_release+0x93/0x640 drivers/media/dvb-core/dmxdev.c:1249
 __fput+0x44f/0xa70 fs/file_table.c:469
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcd3419c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff2d388378 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fcd34417da0 RCX: 00007fcd3419c799
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007fcd34417da0 R08: 00007fcd34416038 R09: 0000000000000000
R10: 00000000003ffd18 R11: 0000000000000246 R12: 0000000000029303
R13: 00007fcd34415fac R14: 0000000000029010 R15: 00007fff2d388480
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dvb_dmxdev_feed_stop drivers/media/dvb-core/dmxdev.c:494 [inline]
RIP: 0010:dvb_dmxdev_filter_stop+0x1a9/0x720 drivers/media/dvb-core/dmxdev.c:572
Code: 00 00 49 8d 5c 24 f8 48 89 d8 48 c1 e8 03 80 3c 28 00 74 08 48 89 df e8 75 f7 47 fa 48 8b 1b 48 8d 7b 28 48 89 f8 48 c1 e8 03 <80> 3c 28 00 74 05 e8 5c f7 47 fa 4c 8b 5b 28 48 89 df 2e e8 db ac
RSP: 0018:ffffc90004327c58 EFLAGS: 00010206
RAX: 0000000000000005 RBX: 0000000000000000 RCX: 0000000000000005
RDX: ffffffff87e8110a RSI: ffffffff8f8e1200 RDI: 0000000000000028
RBP: dffffc0000000000 R08: ffff88803287bd00 R09: 0000000000000002
R10: 0000000000000002 R11: 0000000000000000 R12: ffff888025c1f510
R13: ffffc900064dc540 R14: 1ffff92000c9b8a8 R15: ffffc900064dc4e8
FS:  0000555581367500(0000) GS:ffff88812511b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30263fff CR3: 000000007ef5e000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	49 8d 5c 24 f8       	lea    -0x8(%r12),%rbx
   7:	48 89 d8             	mov    %rbx,%rax
   a:	48 c1 e8 03          	shr    $0x3,%rax
   e:	80 3c 28 00          	cmpb   $0x0,(%rax,%rbp,1)
  12:	74 08                	je     0x1c
  14:	48 89 df             	mov    %rbx,%rdi
  17:	e8 75 f7 47 fa       	call   0xfa47f791
  1c:	48 8b 1b             	mov    (%rbx),%rbx
  1f:	48 8d 7b 28          	lea    0x28(%rbx),%rdi
  23:	48 89 f8             	mov    %rdi,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	80 3c 28 00          	cmpb   $0x0,(%rax,%rbp,1) <-- trapping instruction
  2e:	74 05                	je     0x35
  30:	e8 5c f7 47 fa       	call   0xfa47f791
  35:	4c 8b 5b 28          	mov    0x28(%rbx),%r11
  39:	48 89 df             	mov    %rbx,%rdi
  3c:	2e                   	cs
  3d:	e8                   	.byte 0xe8
  3e:	db                   	.byte 0xdb
  3f:	ac                   	lods   %ds:(%rsi),%al

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/26 22:23 linux-next 7d6661873f6b ffa54287 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce general protection fault in dvb_dmxdev_filter_stop
* Struck through repros no longer work on HEAD.