[PATCH 5.16 17/37] ALSA: pcm: Add stream lock during PCM reset ioctl operations

Greg Kroah-Hartman
2022-03-25T15:27:26Z

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
@@ -1851,11 +1851,13 @@ static int snd_pcm_do_reset(struct snd_p
int err = snd_pcm_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;
}

@@ -1863,10 +1865,12 @@ static void snd_pcm_post_reset(struct sn
snd_pcm_state_t 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 = {