Re: [PATCH v2] ALSA: control: Validate element info in compat ioctl

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Low] ALSA: control: get_ctl_type() duplicates __snd_ctl_elem_info()
--

commit e7c5b72d570147881e5fc3076a50929183e5bf55
Author: Sreeraj S Kurup <sreekuttan2156239@gmail.com>

ALSA: control: Validate element info in compat ioctl

This commit validates control element info in get_ctl_type() for compat
ioctls by rebuilding the element ID, setting the control access flags,
and calling snd_ctl_check_elem_info() when validation is not skipped.

> diff --git a/sound/core/control_compat.c b/sound/core/control_compat.c
> index 87f7ad5ab7391..0c1b80c856f26 100644
> --- a/sound/core/control_compat.c
> +++ b/sound/core/control_compat.c
> @@ -169,6 +169,8 @@ static int get_ctl_type(struct snd_card *card, struct snd_ctl_elem_id *id,
>  			int *countp)
>  {
>  	struct snd_kcontrol *kctl;
> +	struct snd_kcontrol_volatile *vd;
> +	unsigned int index_offset;
>  	int err;
>  
>  	guard(rwsem_read)(&card->controls_rwsem);
> @@ -183,6 +185,17 @@ static int get_ctl_type(struct snd_card *card, struct snd_ctl_elem_id *id,
>  	info->id = *id;
>  	err = kctl->info(kctl, info);
>  	if (err >= 0) {
> +		index_offset = snd_ctl_get_ioff(kctl, &info->id);
> +		vd = &kctl->vd[index_offset];
> +		snd_ctl_build_ioff(&info->id, kctl, index_offset);
> +		info->access = vd->access;
> +
> +		if (!snd_ctl_skip_validation(info)) {
> +			err = snd_ctl_check_elem_info(card, info);
> +			if (err < 0)
> +				return err;
> +		}
> +
>  		err = info->type;
>  		*countp = info->count;
>  	}

[Severity: Low]
Could get_ctl_type() call __snd_ctl_elem_info(card, kctl, info, NULL)
instead of open-coding this sequence?

sound/core/control_compat.c is included directly by sound/core/control.c,
where __snd_ctl_elem_info() already invokes kctl->info(), rebuilds
info->id, sets info->access, and runs snd_ctl_check_elem_info(), just as
snd_ctl_elem_read() and snd_ctl_elem_write() do when passing a NULL
snd_ctl_file pointer.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261108160925.8774-1-sreekuttan2156239@gmail.com?part=1