Code: static bool snd_ctl_remove_numid_conflict(struct snd_card *card,
					  unsigned int count)
 {
 	struct snd_kcontrol *kctl;
 
 	list_for_each_entry(kctl, &card->controls, list) {
 		if (kctl->id.numid < card->last_numid + 1 + count &&
 		    kctl->id.numid + kctl->count > card->last_numid + 1) {
		    	card->last_numid = kctl->id.numid + kctl->count - 1;
			return true;
		}
	}
	return false;
}

Vulnerability Type: DoS Overflow 
CWE ID: CWE-189
Summary: Multiple integer overflows in sound/core/control.c in the ALSA control implementation in the Linux kernel before 3.15.2 allow local users to cause a denial of service by leveraging /dev/snd/controlCX access, related to (1) index values in the snd_ctl_add function and (2) numid values in the snd_ctl_remove_numid_conflict function.
Commit Message: ALSA: control: Handle numid overflow

Each control gets automatically assigned its numids when the control is created.
The allocation is done by incrementing the numid by the amount of allocated
numids per allocation. This means that excessive creation and destruction of
controls (e.g. via SNDRV_CTL_IOCTL_ELEM_ADD/REMOVE) can cause the id to
eventually overflow. Currently when this happens for the control that caused the
overflow kctl->id.numid + kctl->count will also over flow causing it to be
smaller than kctl->id.numid. Most of the code assumes that this is something
that can not happen, so we need to make sure that it won't happen

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Jaroslav Kysela <perex@perex.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>