[alsa-devel] [PATCH] ASoC: core: Fix possible NULL pointer dereference of pcm->config

[Lars-Peter Clausen]

On 01/16/2014 09:08 AM, Xiubo Li wrote:
> Since the soc generic dmaengine pcm driver allows using the defualt settings,
> so the pcm->config maybe NULL.
>
> Signed-off-by: Xiubo Li <Li.Xiubo at freescale.com>

Acked-by: Lars-Peter Clausen <lars at metafoo.de>

Thanks. I actually had the very same patch locally, but overlooked it. It would 
be good if this could make it into 3.14, since the jz4740 conversion to the 
generic dmaengine driver needs this.

> ---
>   sound/soc/soc-generic-dmaengine-pcm.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c
> index 560a778..5bace12 100644
> --- a/sound/soc/soc-generic-dmaengine-pcm.c
> +++ b/sound/soc/soc-generic-dmaengine-pcm.c
> @@ -176,17 +176,20 @@ static struct dma_chan *dmaengine_pcm_compat_request_channel(
>   {
>   	struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
>   	struct snd_dmaengine_dai_dma_data *dma_data;
> +	dma_filter_fn fn = NULL;
>
>   	dma_data = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);
>
>   	if ((pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX) && pcm->chan[0])
>   		return pcm->chan[0];
>
> -	if (pcm->config->compat_request_channel)
> +	if (pcm->config && pcm->config->compat_request_channel)
>   		return pcm->config->compat_request_channel(rtd, substream);
>
> -	return snd_dmaengine_pcm_request_channel(pcm->config->compat_filter_fn,
> -						 dma_data->filter_data);
> +	if (pcm->config)
> +		fn = pcm->config->compat_filter_fn;
> +
> +	return snd_dmaengine_pcm_request_channel(fn, dma_data->filter_data);
>   }
>
>   static bool dmaengine_pcm_can_report_residue(struct dma_chan *chan)
>