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ALSA: pcm: Fix stream lock usage in snd_pcm_period_elapsed() 

If the nullity check for `substream->runtime` is outside of the lock
region, it is possible to have a null runtime in the critical section
if snd_pcm_detach_substream is called right before the lock.

Signed-off-by: paulhsia <paulhsia@chromium.org>
Link: https://lore.kernel.org/r/20191112171715.128727-2-paulhsia@chromium.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
paulhsia 2019-11-13 01:17:14 +08:00 committed by Takashi Iwai
parent 528699317d
commit f5cdc9d400
1 changed files with 6 additions and 2 deletions
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8
sound/core/pcm_lib.c
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@ -1782,11 +1782,14 @@ void snd_pcm_period_elapsed(struct snd_pcm_substream *substream)
struct snd_pcm_runtime *runtime;
unsigned long flags;
if (PCM_RUNTIME_CHECK(substream))
if (snd_BUG_ON(!substream))
return;
runtime = substream->runtime;
snd_pcm_stream_lock_irqsave(substream, flags);
if (PCM_RUNTIME_CHECK(substream))
goto _unlock;
runtime = substream->runtime;
if (!snd_pcm_running(substream) ||
snd_pcm_update_hw_ptr0(substream, 1) < 0)
goto _end;
@ -1797,6 +1800,7 @@ void snd_pcm_period_elapsed(struct snd_pcm_substream *substream)
#endif
_end:
kill_fasync(&runtime->fasync, SIGIO, POLL_IN);
_unlock:
snd_pcm_stream_unlock_irqrestore(substream, flags);
}
EXPORT_SYMBOL(snd_pcm_period_elapsed);