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authorLars-Peter Clausen <lars@metafoo.de>2014-06-18 15:32:31 +0400
committerTakashi Iwai <tiwai@suse.de>2014-06-18 17:12:33 +0400
commit07f4d9d74a04aa7c72c5dae0ef97565f28f17b92 (patch)
tree65d9ee5f96dacb86a33d3a8cd786e876563d93ac /sound/core/init.c
parent7171511eaec5bf23fb06078f59784a3a0626b38f (diff)
downloadlinux-07f4d9d74a04aa7c72c5dae0ef97565f28f17b92.tar.xz
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 'sound/core/init.c')
-rw-r--r--sound/core/init.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/sound/core/init.c b/sound/core/init.c
index 5ee83845c5de..7bdfd19e24a8 100644
--- a/sound/core/init.c
+++ b/sound/core/init.c
@@ -232,6 +232,7 @@ int snd_card_new(struct device *parent, int idx, const char *xid,
INIT_LIST_HEAD(&card->devices);
init_rwsem(&card->controls_rwsem);
rwlock_init(&card->ctl_files_rwlock);
+ mutex_init(&card->user_ctl_lock);
INIT_LIST_HEAD(&card->controls);
INIT_LIST_HEAD(&card->ctl_files);
spin_lock_init(&card->files_lock);