KCSAN: data-race in __snd_pcm_lib_xfer / snd_pcm_kernel_ioctl (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e87297fa Merge tag 'drm-fixes-2020-12-04' of git://anongit..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1206e0f3500000
kernel config: https://syzkaller.appspot.com/x/.config?x=c949fed53798f819
dashboard link: https://syzkaller.appspot.com/bug?extid=c175b85e4b7982b2f99f
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [alsa-...@alsa-project.org ar...@arndb.de baoli...@linaro.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+c175b8...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __snd_pcm_lib_xfer / snd_pcm_kernel_ioctl

write to 0xffff8880143fe000 of 4 bytes by task 21730 on cpu 0:
snd_pcm_post_start sound/core/pcm_native.c:1368 [inline]
snd_pcm_action_single sound/core/pcm_native.c:1209 [inline]
snd_pcm_action sound/core/pcm_native.c:1290 [inline]
snd_pcm_action_lock_irq sound/core/pcm_native.c:1305 [inline]
snd_pcm_start_lock_irq sound/core/pcm_native.c:1398 [inline]
snd_pcm_kernel_ioctl+0x8b7/0xda0 sound/core/pcm_native.c:3331
snd_pcm_oss_set_trigger+0x3cc/0x490 sound/core/oss/pcm_oss.c:2102
snd_pcm_oss_poll+0x429/0x510 sound/core/oss/pcm_oss.c:2831
vfs_poll include/linux/poll.h:90 [inline]
do_pollfd fs/select.c:869 [inline]
do_poll fs/select.c:917 [inline]
do_sys_poll+0x611/0xb80 fs/select.c:1011
__do_sys_ppoll fs/select.c:1111 [inline]
__se_sys_ppoll+0x169/0x1b0 fs/select.c:1091
__x64_sys_ppoll+0x63/0x70 fs/select.c:1091
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880143fe000 of 4 bytes by task 21737 on cpu 1:
pcm_sanity_check sound/core/pcm_lib.c:2067 [inline]
__snd_pcm_lib_xfer+0xea/0x1170 sound/core/pcm_lib.c:2130
snd_pcm_oss_read3+0x291/0x380 sound/core/oss/pcm_oss.c:1260
snd_pcm_oss_read2 sound/core/oss/pcm_oss.c:1471 [inline]
snd_pcm_oss_read1 sound/core/oss/pcm_oss.c:1518 [inline]
snd_pcm_oss_read+0x6e2/0x8a0 sound/core/oss/pcm_oss.c:2742
do_loop_readv_writev fs/read_write.c:761 [inline]
do_iter_read+0x2be/0x4b0 fs/read_write.c:803
vfs_readv fs/read_write.c:921 [inline]
do_readv+0x13d/0x280 fs/read_write.c:958
__do_sys_readv fs/read_write.c:1049 [inline]
__se_sys_readv fs/read_write.c:1046 [inline]
__x64_sys_readv+0x41/0x50 fs/read_write.c:1046
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: 1 PID: 21737 Comm: syz-executor.0 Not tainted 5.10.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

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