Re: fix usbmixer double kfree.

[Andrew Morton <akpm@osdl.org>]

Dave Jones <davej@redhat.com> wrote:
>
> snd_ctl_add() kfree's the kcontrol already if we fail there,
> so this driver is currently doing a double kfree.

Well sometimes it does.  If we hit one of those snd_assert() abominations,
snd_ctl_add() will return error without freeing the kcontrol.

Still, a leak is better than a double-free.

> --- linux-2.6/sound/usb/usbmixer.c~	2006-03-06 03:40:20.000000000 -0500
> +++ linux-2.6/sound/usb/usbmixer.c	2006-03-06 03:45:03.000000000 -0500
> @@ -434,7 +434,6 @@ static int add_control_to_empty(struct m
>  		kctl->id.index++;
>  	if ((err = snd_ctl_add(state->chip->card, kctl)) < 0) {
>  		snd_printd(KERN_ERR "cannot add control (err = %d)\n", err);
> -		snd_ctl_free_one(kctl);
>  		return err;
>  	}
>  	cval->elem_id = &kctl->id;