[PATCH 4.19 09/20] ALSA: pcm: Add stream lock during PCM reset ioctl operations

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Takashi Iwai <tiwai@suse.de>

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: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20220322171325.4355-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 sound/core/pcm_native.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1648,21 +1648,25 @@ static int snd_pcm_do_reset(struct snd_p
 	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 = {