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Commit 9d721cdd authored by Takashi Iwai's avatar Takashi Iwai Committed by Greg Kroah-Hartman
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ALSA: pcm: Add stream lock during PCM reset ioctl operations 



commit 1f68915b2efd0d6bfd6e124aa63c94b3c69f127c upstream.

snd_pcm_reset() is a non-atomic operation, and it's allowed to run
during the PCM stream running.  It implies that the manipulation of
hw_ptr and other parameters might be racy.

This patch adds the PCM stream lock at appropriate places in
snd_pcm_*_reset() actions for covering that.

Cc: <stable@vger.kernel.org>
Reviewed-by: default avatarJaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20220322171325.4355-1-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a63af1ba

sound/core/pcm_native.c

+4 −0
Original line number Diff line number Diff line
@@ -1648,21 +1648,25 @@ static int snd_pcm_do_reset(struct snd_pcm_substream *substream, int state) 
	int err = substream->ops->ioctl(substream, SNDRV_PCM_IOCTL1_RESET, NULL);

	if (err < 0)

		return err;

	snd_pcm_stream_lock_irq(substream);

	runtime->hw_ptr_base = 0;

	runtime->hw_ptr_interrupt = runtime->status->hw_ptr -

		runtime->status->hw_ptr % runtime->period_size;

	runtime->silence_start = runtime->status->hw_ptr;

	runtime->silence_filled = 0;

	snd_pcm_stream_unlock_irq(substream);

	return 0;

}



static void snd_pcm_post_reset(struct snd_pcm_substream *substream, int state)

{

	struct snd_pcm_runtime *runtime = substream->runtime;

	snd_pcm_stream_lock_irq(substream);

	runtime->control->appl_ptr = runtime->status->hw_ptr;

	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&

	    runtime->silence_size > 0)

		snd_pcm_playback_silence(substream, ULONG_MAX);

	snd_pcm_stream_unlock_irq(substream);

}



static const struct action_ops snd_pcm_action_reset = {