KCSAN: data-race in snd_seq_oss_midi_close / snd_seq_oss_midi_open

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fa02fcd9 Merge tag 'media/v5.10-2' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10138349500000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9b19d1bde60f8d
dashboard link: https://syzkaller.appspot.com/bug?extid=93be2acc84f1d19115ed
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [alsa-...@alsa-project.org linux-...@vger.kernel.org pe...@perex.cz ti...@suse.com]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+93be2a...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in snd_seq_oss_midi_close / snd_seq_oss_midi_open

write to 0xffff888105bdd1c0 of 8 bytes by task 30387 on cpu 1:
snd_seq_oss_midi_close+0x263/0x2a0 sound/core/seq/oss/seq_oss_midi.c:409
snd_seq_oss_midi_cleanup+0x3b/0x80 sound/core/seq/oss/seq_oss_midi.c:281
snd_seq_oss_release+0x7a/0x160 sound/core/seq/oss/seq_oss_init.c:415
odev_release+0x3a/0x60 sound/core/seq/oss/seq_oss.c:140
__fput+0x243/0x4d0 fs/file_table.c:281
____fput+0x11/0x20 fs/file_table.c:314
task_work_run+0x8e/0x110 kernel/task_work.c:151
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_user_mode_loop kernel/entry/common.c:164 [inline]
exit_to_user_mode_prepare+0x13c/0x170 kernel/entry/common.c:191
syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888105bdd1c0 of 8 bytes by task 30391 on cpu 0:
snd_seq_oss_midi_open+0xd4/0x3b0 sound/core/seq/oss/seq_oss_midi.c:325
snd_seq_oss_process_event+0x5b3/0xf40 sound/core/seq/oss/seq_oss_event.c:69
insert_queue sound/core/seq/oss/seq_oss_rw.c:166 [inline]
snd_seq_oss_write+0x319/0x550 sound/core/seq/oss/seq_oss_rw.c:135
odev_write+0x45/0x60 sound/core/seq/oss/seq_oss.c:164
vfs_write+0x21a/0x7c0 fs/read_write.c:603
ksys_write+0xce/0x180 fs/read_write.c:658
__do_sys_write fs/read_write.c:670 [inline]
__se_sys_write fs/read_write.c:667 [inline]
__x64_sys_write+0x3e/0x50 fs/read_write.c:667
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 30391 Comm: syz-executor.1 Not tainted 5.10.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.