ALSA: control: Don't access controls outside of protected regions

ALSA: control: Don't access controls outside of protected regions

(commit fd9f26e4eca5d08a27d12c0933fceef76ed9663d upstream)

A control that is visible on the card->controls list can be freed at any time.
This means we must not access any of its memory while not holding the
controls_rw_lock. Otherwise we risk a use after free access.

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>
[wt: fixes CVE-2014-4653]
Signed-off-by: Willy Tarreau <w@1wt.eu>