[moderation] [sound?] KCSAN: data-race in snd_fasync_helper / snd_timer_user_ccallback

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8d025e2092e2 Merge tag 'erofs-for-6.9-rc2-fixes' of git://..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11c1e5e6180000
kernel config: https://syzkaller.appspot.com/x/.config?x=aa27611f143168c9
dashboard link: https://syzkaller.appspot.com/bug?extid=29f860c5b65d73753038
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [linux-...@vger.kernel.org linux...@vger.kernel.org pe...@perex.cz ti...@suse.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/25a7994bce97/disk-8d025e20.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fd186f3a786f/vmlinux-8d025e20.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a958ca120141/bzImage-8d025e20.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+29f860...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in snd_fasync_helper / snd_timer_user_ccallback

write to 0xffff888113b968c8 of 8 bytes by task 12923 on cpu 1:
snd_fasync_helper+0xd2/0x130 sound/core/misc.c:210
snd_timer_user_fasync+0x3a/0x50 sound/core/timer.c:2066
ioctl_fioasync fs/ioctl.c:380 [inline]
do_vfs_ioctl+0xe7c/0x1560 fs/ioctl.c:819
__do_sys_ioctl fs/ioctl.c:902 [inline]
__se_sys_ioctl+0x81/0x150 fs/ioctl.c:890
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:890
do_syscall_64+0xd3/0x1d0
entry_SYSCALL_64_after_hwframe+0x6d/0x75

read to 0xffff888113b968c8 of 8 bytes by task 12924 on cpu 0:
snd_timer_user_ccallback+0x24b/0x290 sound/core/timer.c:1338
snd_timer_notify1+0x12d/0x240 sound/core/timer.c:514
snd_timer_start1+0x396/0x3c0 sound/core/timer.c:569
snd_timer_start sound/core/timer.c:665 [inline]
snd_timer_user_start+0x10d/0x160 sound/core/timer.c:1915
__snd_timer_user_ioctl+0x3ee/0x2450
snd_timer_user_ioctl+0x4b/0x80 sound/core/timer.c:2058
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:904 [inline]
__se_sys_ioctl+0xd3/0x150 fs/ioctl.c:890
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:890
do_syscall_64+0xd3/0x1d0
entry_SYSCALL_64_after_hwframe+0x6d/0x75

value changed: 0x0000000000000000 -> 0xffff888138986c40

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12924 Comm: syz-executor.4 Not tainted 6.9.0-rc1-syzkaller-00061-g8d025e2092e2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
==================================================================


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