Re: [PATCH 1/4] ASoC: codec2codec: avoid invalid/double-free of pcm runtime

[Jerome Brunet]

On Thu 13 Feb 2020 at 07:11, Samuel Holland <samuel@xxxxxxxxxxxx> wrote:

> The PCM runtime was freed during PMU in the case that the event hook
> encountered an error. However, it is also unconditionally freed during
> PMD. Avoid a double-free by dropping the call to kfree in the PMU
> hook.

Oh ... Thanks for finding this.

I thought that a widget which has failed PMU would not go through PMD,
but It seems the return value dapm_seq_check_event is not checked.

This brings another question/problem:
A link which has failed in PMU, could try in PMD to hw_free/shutdown a
dai which has not gone through startup/hw_params, right ?

>
> Fixes: a72706ed8208 ("ASoC: codec2codec: remove ephemeral variables")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Samuel Holland <samuel@xxxxxxxxxxxx>
> ---
>  sound/soc/soc-dapm.c | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c
> index b6378f025836..935b5375ecc5 100644
> --- a/sound/soc/soc-dapm.c
> +++ b/sound/soc/soc-dapm.c
> @@ -3888,9 +3888,6 @@ snd_soc_dai_link_event_pre_pmu(struct snd_soc_dapm_widget *w,
>  	runtime->rate = params_rate(params);
>  
>  out:
> -	if (ret < 0)
> -		kfree(runtime);
> -
>  	kfree(params);
>  	return ret;
>  }