ALSA: control: Protect user controls against concurrent access
authorLars-Peter Clausen <lars@metafoo.de>
Wed, 18 Jun 2014 11:32:31 +0000 (13:32 +0200)
committerTakashi Iwai <tiwai@suse.de>
Wed, 18 Jun 2014 13:12:33 +0000 (15:12 +0200)
commit07f4d9d74a04aa7c72c5dae0ef97565f28f17b92
tree65d9ee5f96dacb86a33d3a8cd786e876563d93ac
parent7171511eaec5bf23fb06078f59784a3a0626b38f
ALSA: control: Protect user controls against concurrent access

The user-control put and get handlers as well as the tlv do not protect against
concurrent access from multiple threads. Since the state of the control is not
updated atomically it is possible that either two write operations or a write
and a read operation race against each other. Both can lead to arbitrary memory
disclosure. This patch introduces a new lock that protects user-controls from
concurrent access. Since applications typically access controls sequentially
than in parallel a single lock per card should be fine.

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>
include/sound/core.h
sound/core/control.c
sound/core/init.c