Re: [PATCH v2] ASoC: qcom: q6apm-lpass-dais: Fix NULL pointer dereference if source graph failed

[Srinivas Kandagatla <srinivas.kandagatla@oss.qualcomm.com>]

On 9/4/25 11:18 AM, Krzysztof Kozlowski wrote:
> If earlier opening of source graph fails (e.g. ADSP rejects due to
> incorrect audioreach topology), the graph is closed and
> "dai_data->graph[dai->id]" is assigned NULL.  Preparing the DAI for sink
> graph continues though and next call to q6apm_lpass_dai_prepare()
> receives dai_data->graph[dai->id]=NULL leading to NULL pointer
> exception:
> 
>   qcom-apm gprsvc:service:2:1: Error (1) Processing 0x01001002 cmd
>   qcom-apm gprsvc:service:2:1: DSP returned error[1001002] 1
>   q6apm-lpass-dais 30000000.remoteproc:glink-edge:gpr:service@1:bedais: fail to start APM port 78
>   q6apm-lpass-dais 30000000.remoteproc:glink-edge:gpr:service@1:bedais: ASoC: error at snd_soc_pcm_dai_prepare on TX_CODEC_DMA_TX_3: -22
>   Unable to handle kernel NULL pointer dereference at virtual address 00000000000000a8
>   ...
>   Call trace:
>    q6apm_graph_media_format_pcm+0x48/0x120 (P)
>    q6apm_lpass_dai_prepare+0x110/0x1b4
>    snd_soc_pcm_dai_prepare+0x74/0x108
>    __soc_pcm_prepare+0x44/0x160
>    dpcm_be_dai_prepare+0x124/0x1c0
> 
> Fixes: 30ad723b93ad ("ASoC: qdsp6: audioreach: add q6apm lpass dai support")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> 
> ---
> 
> Changes in v2:
> 1. Use approach suggested by Srini (you gave me some code, so shall I
>    add Co-developed-by?)
don't worry about it.


LGTM,

Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@oss.qualcomm.com>


--srini
> ---
>  sound/soc/qcom/qdsp6/q6apm-lpass-dais.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/soc/qcom/qdsp6/q6apm-lpass-dais.c b/sound/soc/qcom/qdsp6/q6apm-lpass-dais.c
> index a0d90462fd6a..20974f10406b 100644
> --- a/sound/soc/qcom/qdsp6/q6apm-lpass-dais.c
> +++ b/sound/soc/qcom/qdsp6/q6apm-lpass-dais.c
> @@ -213,8 +213,10 @@ static int q6apm_lpass_dai_prepare(struct snd_pcm_substream *substream, struct s
>  
>  	return 0;
>  err:
> -	q6apm_graph_close(dai_data->graph[dai->id]);
> -	dai_data->graph[dai->id] = NULL;
> +	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
> +		q6apm_graph_close(dai_data->graph[dai->id]);
> +		dai_data->graph[dai->id] = NULL;
> +	}
>  	return rc;
>  }
>