[PATCH] ASoC: SOF: Intel: Fix stream cleanup on pcm close

[Pierre-Louis Bossart]

On 2/18/20 8:10 AM, Cezary Rojewski wrote:
> Field "substream" gets assigned during stream setup in
> hda_dsp_pcm_hw_params() but it is never cleared afterwards during
> hda_dsp_pcm_close(). Now, any non-pcm operation e.g.: compress can
> mistakenly make use of that pointer as it's bypassing all
> "if (s->substream)" checks.
> 
> Nulling the pointer during close operation ensures no wild pointers are
> left behind.
> 
> Fixes: cdae3b9a47aa ("ASoC: SOF: Intel: Add Intel specific HDA PCM operations")
> Signed-off-by: Cezary Rojewski <cezary.rojewski at intel.com>
> ---
>   sound/soc/sof/intel/hda-pcm.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/sound/soc/sof/intel/hda-pcm.c b/sound/soc/sof/intel/hda-pcm.c
> index a46a6baa1c3f..4b3a89cf20e7 100644
> --- a/sound/soc/sof/intel/hda-pcm.c
> +++ b/sound/soc/sof/intel/hda-pcm.c
> @@ -246,5 +246,6 @@ int hda_dsp_pcm_close(struct snd_sof_dev *sdev,
>   
>   	/* unbinding pcm substream to hda stream */
>   	substream->runtime->private_data = NULL;
> +	hstream->substream = NULL;
>   	return 0;
>   }


Humm, yes we should clean this, but wondering if the close() operation 
is the right place. Doing this is hda_dsp_stream_hw_free() sounds more 
logical to me?