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authorLars-Peter Clausen <lars@metafoo.de>2014-06-18 13:32:31 +0200
committerTakashi Iwai <tiwai@suse.de>2014-06-18 15:12:33 +0200
commit07f4d9d74a04aa7c72c5dae0ef97565f28f17b92 (patch)
tree65d9ee5f96dacb86a33d3a8cd786e876563d93ac /include
parent7171511eaec5bf23fb06078f59784a3a0626b38f (diff)
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>
Diffstat (limited to 'include')
-rw-r--r--include/sound/core.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/sound/core.h b/include/sound/core.h
index eedda2cdfe57..1df3f2fe5350 100644
--- a/include/sound/core.h
+++ b/include/sound/core.h
@@ -116,6 +116,8 @@ struct snd_card {
int user_ctl_count; /* count of all user controls */
struct list_head controls; /* all controls for this card */
struct list_head ctl_files; /* active control files */
+ struct mutex user_ctl_lock; /* protects user controls against
+ concurrent access */
struct snd_info_entry *proc_root; /* root for soundcard specific files */
struct snd_info_entry *proc_id; /* the card id */

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