Currently kill_fasync() is called outside the stream lock in snd_pcm_period_elapsed(). This is potentially racy, since the stream may get released even during the irq handler is running. Although snd_pcm_release_substream() calls snd_pcm_drop(), this doesn't guarantee that the irq handler finishes, thus the kill_fasync() call outside the stream spin lock may be invoked after the substream is detached, as recently reported by KASAN.

As a quick workaround, move kill_fasync() call inside the stream lock. The fasync is rarely used interface, so this shouldn't have a big impact from the performance POV.

Ideally, we should implement some sync mechanism for the proper finish of stream and irq handler. But this oneliner should suffice for most cases, so far.

Reported-by: Baozeng Ding sploving1@gmail.com Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/core/pcm_lib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 3a9b66c6e09c..0aca39762ed0 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -1886,8 +1886,8 @@ void snd_pcm_period_elapsed(struct snd_pcm_substream *substream) snd_timer_interrupt(substream->timer, 1); #endif _end: - snd_pcm_stream_unlock_irqrestore(substream, flags); kill_fasync(&runtime->fasync, SIGIO, POLL_IN); + snd_pcm_stream_unlock_irqrestore(substream, flags); }

EXPORT_SYMBOL(snd_pcm_period_elapsed);