[syzbot] [media?] WARNING in vidtv_stop_feed
From: syzbot
Date: Thu Aug 27 2026 - 22:46:02 EST
Hello,
syzbot found the following issue on:
HEAD commit: 388b607d107c Merge tag 'efi-next-for-v7.3' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10a42625580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b57978e7637d0f4a
dashboard link: https://syzkaller.appspot.com/bug?extid=3157015c6bd85395cddc
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
userspace arch: i386
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-388b607d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a21f6d431a2a/vmlinux-388b607d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5f0615983131/bzImage-388b607d.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3157015c6bd85395cddc@xxxxxxxxxxxxxxxxxxxxxxxxx
------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(lock->magic != lock)
WARNING: kernel/locking/mutex.c:625 at __mutex_lock_common kernel/locking/mutex.c:625 [inline], CPU#3: syz.3.334/7114
WARNING: kernel/locking/mutex.c:625 at __mutex_lock+0x944/0x1bc0 kernel/locking/mutex.c:821, CPU#3: syz.3.334/7114
Modules linked in:
CPU: 3 UID: 0 PID: 7114 Comm: syz.3.334 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__mutex_lock_common kernel/locking/mutex.c:625 [inline]
RIP: 0010:__mutex_lock+0x94b/0x1bc0 kernel/locking/mutex.c:821
Code: 0f b6 14 11 38 d0 7c 08 84 d2 0f 85 b4 10 00 00 44 8b 05 b8 11 7a 05 45 85 c0 75 13 48 8d 3d 9c 16 7d 05 48 c7 c6 80 d3 ef 8b <67> 48 0f b9 3a 90 e9 1b f8 ff ff 4d 8d a7 f0 0a 00 00 4c 89 e7 e8
RSP: 0000:ffffc90025f2fae0 EFLAGS: 00010246
RAX: 0000000000000003 RBX: ffff888029f2d128 RCX: 1ffffffff22898cc
RDX: 0000000000000000 RSI: ffffffff8befd380 RDI: ffffffff9147cb50
RBP: ffffc90025f2fc50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888096c84000(0063) knlGS:0000000057892480
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f544aff4 CR3: 00000000577a8000 CR4: 0000000000352ef0
Call Trace:
<TASK>
vidtv_stop_feed+0x75/0x2a0 drivers/media/test-drivers/vidtv/vidtv_bridge.c:256
dmx_ts_feed_stop_filtering+0xe9/0x1d0 drivers/media/dvb-core/dvb_demux.c:780
dvb_dmxdev_feed_stop.isra.0+0x162/0x270 drivers/media/dvb-core/dmxdev.c:494
dvb_dmxdev_filter_stop+0x1d0/0x390 drivers/media/dvb-core/dmxdev.c:572
dvb_dmxdev_filter_free drivers/media/dvb-core/dmxdev.c:856 [inline]
dvb_demux_release+0x92/0x560 drivers/media/dvb-core/dmxdev.c:1256
__fput+0x3ff/0xb50 fs/file_table.c:512
task_work_run+0x150/0x240 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+0x1d8/0x700 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_fast_syscall_32+0x59f/0x8b0 arch/x86/entry/syscall_32.c:294
do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:316
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf6ffefec
Code: Unable to access opcode bytes at 0xf6ffefc2.
RSP: 002b:00000000ffb45dfc EFLAGS: 00000202 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 000000000000001e
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
----------------
Code disassembly (best guess):
0: 0f b6 14 11 movzbl (%rcx,%rdx,1),%edx
4: 38 d0 cmp %dl,%al
6: 7c 08 jl 0x10
8: 84 d2 test %dl,%dl
a: 0f 85 b4 10 00 00 jne 0x10c4
10: 44 8b 05 b8 11 7a 05 mov 0x57a11b8(%rip),%r8d # 0x57a11cf
17: 45 85 c0 test %r8d,%r8d
1a: 75 13 jne 0x2f
1c: 48 8d 3d 9c 16 7d 05 lea 0x57d169c(%rip),%rdi # 0x57d16bf
23: 48 c7 c6 80 d3 ef 8b mov $0xffffffff8befd380,%rsi
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: 90 nop
30: e9 1b f8 ff ff jmp 0xfffff850
35: 4d 8d a7 f0 0a 00 00 lea 0xaf0(%r15),%r12
3c: 4c 89 e7 mov %r12,%rdi
3f: e8 .byte 0xe8
---
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