syzbot

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

write to 0xffff88810e589000 of 4 bytes by task 26390 on cpu 0:
 snd_pcm_post_start sound/core/pcm_native.c:1373 [inline]
 snd_pcm_action_single sound/core/pcm_native.c:1214 [inline]
 snd_pcm_action sound/core/pcm_native.c:1295 [inline]
 snd_pcm_action_lock_irq sound/core/pcm_native.c:1310 [inline]
 snd_pcm_start_lock_irq sound/core/pcm_native.c:1403 [inline]
 snd_pcm_kernel_ioctl+0x8ca/0xdc0 sound/core/pcm_native.c:3338
 snd_pcm_oss_set_trigger+0x3cc/0x490 sound/core/oss/pcm_oss.c:2112
 snd_pcm_oss_poll+0x429/0x510 sound/core/oss/pcm_oss.c:2841
 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+0x622/0xc40 fs/select.c:1011
 __do_sys_ppoll fs/select.c:1117 [inline]
 __se_sys_ppoll+0x169/0x1b0 fs/select.c:1097
 __x64_sys_ppoll+0x63/0x70 fs/select.c:1097
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88810e589000 of 4 bytes by task 26393 on cpu 1:
 pcm_sanity_check sound/core/pcm_lib.c:2067 [inline]
 __snd_pcm_lib_xfer+0xe9/0x11e0 sound/core/pcm_lib.c:2130
 snd_pcm_oss_read3+0x2a1/0x390 sound/core/oss/pcm_oss.c:1266
 io_capture_transfer+0x7a/0x2d0 sound/core/oss/io.c:73
 snd_pcm_plug_read_transfer+0x20f/0x2a0 sound/core/oss/pcm_plugin.c:655
 snd_pcm_oss_read2 sound/core/oss/pcm_oss.c:1467 [inline]
 snd_pcm_oss_read1 sound/core/oss/pcm_oss.c:1524 [inline]
 snd_pcm_oss_read+0x55a/0x8e0 sound/core/oss/pcm_oss.c:2752
 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/0x290 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+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 26393 Comm: syz-executor.5 Not tainted 5.12.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================