The snd_ctl_elem_add function in sound/core/control.c in the ALSA control implementation in the Linux kernel before 3.15.2 does not check authorization for SNDRV_CTL_IOCTL_ELEM_REPLACE commands, which allows local users to remove kernel controls and cause a denial of service (use-after-free and system crash) by leveraging /dev/snd/controlCX access for an ioctl call.
