WARNING in snd_pcm_drop

Status: fixed on 2020/10/05 13:19
Fix commit: c5c6e00f6cc5 fix regression in "epoll: Keep a reference on files added to the check list"
First crash: 885d, last: 885d

Fix bisection: fixed by (bisect log) :
commit c5c6e00f6cc5d3ed0d6464b14e33f2f5c8505888
Author: Al Viro <>
Date: Wed Sep 2 15:30:48 2020 +0000

  fix regression in "epoll: Keep a reference on files added to the check list"

similar bugs (1):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 WARNING in snd_pcm_drop syz done 1 884d 884d 1/1 fixed on 2020/10/07 06:25

Sample crash report:
Bluetooth: hci0 command 0x041b tx timeout
Bluetooth: hci0 command 0x040f tx timeout
Bluetooth: hci0 command 0x0419 tx timeout
------------[ cut here ]------------
WARNING: CPU: 1 PID: 8992 at sound/core/pcm_native.c:1901 snd_pcm_drop+0x20f/0x2e0 sound/core/pcm_native.c:1901
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 8992 Comm: syz-executor.0 Not tainted 4.14.196-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 panic+0x1f9/0x42d kernel/panic.c:183
 __warn.cold+0x20/0x4b kernel/panic.c:547
 report_bug+0x208/0x249 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:177 [inline]
 fixup_bug arch/x86/kernel/traps.c:172 [inline]
 do_error_trap+0x195/0x2d0 arch/x86/kernel/traps.c:295
 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:964
RIP: 0010:snd_pcm_drop+0x20f/0x2e0 sound/core/pcm_native.c:1901
RSP: 0018:ffff88809e71fd70 EFLAGS: 00010297
RAX: ffff888087382580 RBX: ffff88809b6d7680 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff86e46280 RDI: ffff88809b6d77d8
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: ffff888087382580 R12: ffff88809b6d7970
R13: ffff8880985bb300 R14: ffff88821626b268 R15: ffff88809f6cc5d0
 snd_pcm_release_substream.part.0+0x21/0x2d0 sound/core/pcm_native.c:2375
 snd_pcm_release_substream sound/core/pcm_native.c:2372 [inline]
 snd_pcm_release+0xe0/0x1f0 sound/core/pcm_native.c:2558
 __fput+0x25f/0x7a0 fs/file_table.c:210
 task_work_run+0x11f/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
RIP: 0033:0x45d5b9
RSP: 002b:00007fdd1277ec78 EFLAGS: 00000246 ORIG_RAX: 00000000000000e9
RAX: 0000000000000000 RBX: 0000000000002ac0 RCX: 000000000045d5b9
RDX: 0000000000000005 RSI: 0000000000000001 RDI: 0000000000000006
RBP: 000000000118d028 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000020000040 R11: 0000000000000246 R12: 000000000118cfec
R13: 00007ffe481cc38f R14: 00007fdd1277f9c0 R15: 000000000118cfec
Kernel Offset: disabled
Rebooting in 86400 seconds..

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets Title
ci2-linux-4-14 2020/09/05 02:42 linux-4.14.y 2f166cdcf8a9 abf9ba4f .config console log report syz
* Struck through repros no longer work on HEAD.