Re: [alsa-devel] [PATCH v2] ALSA: ASoC: soc-compress.c: fix NULL dereference

On Tue, Jan 13, 2015 at 11:18:53AM +0000, Qais Yousef wrote:

In soc_new_compress() when rtd->dai_link->daynmic is set, we create the pcm

^^^^^^^^ typo

substreams with this call:

ret = snd_pcm_new_internal(rtd->card->snd_card, new_name, num, 1, 0, &be_pcm);

which passes 0 as capture_count leading to

be_pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream

being NULL, hence when trying to set rtd a few lines below we get an oops.

It is a good practice to add the oops here

Fix by using rtd->dai_link->dpcm_playback and rtd->dai_link->dpcm_capture as playback_count and capture_count to snd_pcm_new_internal().

Signed-off-by: Qais Yousef qais.yousef@imgtec.com Cc: Vinod Koul vinod.koul@intel.com Cc: Liam Girdwood lgirdwood@gmail.com Cc: Mark Brown broonie@kernel.org Cc: Jaroslav Kysela perex@perex.cz Cc: Takashi Iwai tiwai@suse.de Cc: linux-kernel@vger.kernel.org

---

v2->v1:

• use better way to fix it than just removing the line that caused the oops

sound/soc/soc-compress.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/sound/soc/soc-compress.c b/sound/soc/soc-compress.c index 590a82f01d0b..27a668463ad7 100644 --- a/sound/soc/soc-compress.c +++ b/sound/soc/soc-compress.c @@ -659,7 +659,8 @@ int soc_new_compress(struct snd_soc_pcm_runtime *rtd, int num) rtd->dai_link->stream_name);

ret = snd_pcm_new_internal(rtd->card->snd_card, new_name, num,

• 		1, 0, &be_pcm);
  

• 		rtd->dai_link->dpcm_playback,
  

• 		rtd->dai_link->dpcm_capture, &be_pcm);
  

  if (ret < 0) { dev_err(rtd->card->dev, "ASoC: can't create compressed for %s\n", rtd->dai_link->name);

@@ -668,8 +669,10 @@ int soc_new_compress(struct snd_soc_pcm_runtime *rtd, int num)

rtd->pcm = be_pcm;
rtd->fe_compr = 1;

• be_pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream->private_data = rtd;
  

• be_pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream->private_data = rtd;
  

• if (rtd->dai_link->dpcm_playback)
  

• 	be_pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream->private_data = rtd;
  

• if (rtd->dai_link->dpcm_capture)
  

this should be else if, as for compressed device we can have playback or capture not both

• 	be_pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream->private_data = rtd;
  

  memcpy(compr->ops, &soc_compr_dyn_ops, sizeof(soc_compr_dyn_ops)); } else memcpy(compr->ops, &soc_compr_ops, sizeof(soc_compr_ops));

-- 2.1.0