tree 65d9ee5f96dacb86a33d3a8cd786e876563d93ac
parent 7171511eaec5bf23fb06078f59784a3a0626b38f
author Lars-Peter Clausen <lars@metafoo.de> 1403091151 +0200
committer Takashi Iwai <tiwai@suse.de> 1403097153 +0200

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>