[moderation] [media?] general protection fault in dvb_dmxdev_filter_stop (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 786262be6048 Merge tag 'edac_updates_for_v7.3_rc2' of git:..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1161bb79580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b454dc6b1b7acd30
dashboard link: https://syzkaller.appspot.com/bug?extid=3aa88435ff6e5f9f69a8
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [linux-...@vger.kernel.org linux...@vger.kernel.org mch...@kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c3e528ebf709/disk-786262be.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/46f3418d2828/vmlinux-786262be.xz
kernel image: https://storage.googleapis.com/syzbot-assets/60ab8a27c4f7/bzImage-786262be.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3aa884...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
CPU: 0 UID: 0 PID: 6439 Comm: syz.1.248 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:dvb_dmxdev_feed_stop drivers/media/dvb-core/dmxdev.c:494 [inline]
RIP: 0010:dvb_dmxdev_filter_stop+0x19f/0x700 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 ef 4c a5 fa 48 8b 1b 48 8d 7b 28 48 89 f8 48 c1 e8 03 <80> 3c 28 00 74 05 e8 d6 4c a5 fa 4c 8b 5b 28 48 89 df 2e 2e 2e 41
RSP: 0018:ffffc90006e67c70 EFLAGS: 00010206
RAX: 0000000000000005 RBX: 0000000000000000 RCX: 0000000000000005
RDX: ffffffff878cdb3a RSI: ffffffff8f0c10f0 RDI: 0000000000000028
RBP: dffffc0000000000 R08: ffff888035db8000 R09: 0000000000000002
R10: 0000000000000100 R11: 0000000000000002 R12: ffff88802be5fb90
R13: 1ffff92000fdb80c R14: ffffc90007edc054 R15: ffffc90007edc008
FS: 000055557bd66500(0000) GS:ffff888125bd6000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd2b3595690 CR3: 0000000031a3c000 CR4: 00000000003526f0
Call Trace:
<TASK>
dvb_dmxdev_filter_free drivers/media/dvb-core/dmxdev.c:856 [inline]
dvb_demux_release+0x9b/0x6b0 drivers/media/dvb-core/dmxdev.c:1256
__fput+0x42a/0xa80 fs/file_table.c:512
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:70 [inline]
exit_to_user_mode_loop+0x204/0x770 kernel/entry/common.c:101
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f432b08e159
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:00007ffe1f2da618 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f432b317da0 RCX: 00007f432b08e159
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f432b317da0 R08: 00007f432b316218 R09: 0000000000000000
R10: 00000000005f6dc4 R11: 0000000000000246 R12: 00000000000210f4
R13: 00007f432b31618c R14: 0000000000020e82 R15: 00007ffe1f2da720
</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+0x19f/0x700 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 ef 4c a5 fa 48 8b 1b 48 8d 7b 28 48 89 f8 48 c1 e8 03 <80> 3c 28 00 74 05 e8 d6 4c a5 fa 4c 8b 5b 28 48 89 df 2e 2e 2e 41
RSP: 0018:ffffc90006e67c70 EFLAGS: 00010206
RAX: 0000000000000005 RBX: 0000000000000000 RCX: 0000000000000005
RDX: ffffffff878cdb3a RSI: ffffffff8f0c10f0 RDI: 0000000000000028
RBP: dffffc0000000000 R08: ffff888035db8000 R09: 0000000000000002
R10: 0000000000000100 R11: 0000000000000002 R12: ffff88802be5fb90
R13: 1ffff92000fdb80c R14: ffffc90007edc054 R15: ffffc90007edc008
FS: 000055557bd66500(0000) GS:ffff888125bd6000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd2b3595690 CR3: 0000000031a3c000 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 ef 4c a5 fa call 0xfaa54d0b
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 d6 4c a5 fa call 0xfaa54d0b
35: 4c 8b 5b 28 mov 0x28(%rbx),%r11
39: 48 89 df mov %rbx,%rdi
3c: 2e cs
3d: 2e cs
3e: 2e cs
3f: 41 rex.B


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