Re: [PATCH alsa-lib 1/8] topology: decode: fix channel map memory allocation

[Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>]

On 6/25/20 6:03 AM, Piotr Maziarz wrote:
> Without proper memory allocation behaviour was undefined.

Maybe elaborate to explain that memory allocated on the stack was 
referenced outside of the function scope?

> Signed-off-by: Piotr Maziarz <piotrx.maziarz@xxxxxxxxxxxxxxx>
> ---
>   src/topology/ctl.c | 11 +++++------
>   1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/src/topology/ctl.c b/src/topology/ctl.c
> index 90241b6..c8c7e94 100644
> --- a/src/topology/ctl.c
> +++ b/src/topology/ctl.c
> @@ -1330,7 +1330,6 @@ int tplg_decode_control_enum1(snd_tplg_t *tplg,
>   			      void *bin, size_t size)
>   {
>   	struct snd_soc_tplg_enum_control *ec = bin;
> -	struct snd_tplg_channel_map_template cmt;
>   	int i;
>   
>   	if (size < sizeof(*ec)) {
> @@ -1375,11 +1374,11 @@ int tplg_decode_control_enum1(snd_tplg_t *tplg,
>   		}
>   	}
>   
> -	et->map = &cmt;
> -	memset(&cmt, 0, sizeof(cmt));
> -	cmt.num_channels = ec->num_channels;
> -	for (i = 0; i < cmt.num_channels; i++) {
> -		struct snd_tplg_channel_elem *channel = &cmt.channel[i];
> +	et->map = tplg_calloc(heap, sizeof(struct snd_tplg_channel_map_template));

if (!et->map)
    return -ENOMEM;

> +	et->map->num_channels = ec->num_channels;
> +	for (i = 0; i < et->map->num_channels; i++) {
> +		struct snd_tplg_channel_elem *channel = &et->map->channel[i];
> +
>   		tplg_log(tplg, 'D', pos + ((void *)&ec->channel[i] - (void *)ec),
>   			 "enum: channel size %d", ec->channel[i].size);
>   		channel->reg = ec->channel[i].reg;