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authorSakari Ailus <sakari.ailus@linux.intel.com>2018-09-11 05:32:37 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-10-10 08:52:10 +0200
commitbbbc4dabca5d51c608b0fd608eb3cd8659266653 (patch)
tree5bdfcf58e9ad37d942433b9eccdda7d405837593 /include/media
parentae22586bb579b89c43231a206f074a181a04da13 (diff)
media: v4l: event: Prevent freeing event subscriptions while accessed
commit ad608fbcf166fec809e402d548761768f602702c upstream. The event subscriptions are added to the subscribed event list while holding a spinlock, but that lock is subsequently released while still accessing the subscription object. This makes it possible to unsubscribe the event --- and freeing the subscription object's memory --- while the subscription object is simultaneously accessed. Prevent this by adding a mutex to serialise the event subscription and unsubscription. This also gives a guarantee to the callback ops that the add op has returned before the del op is called. This change also results in making the elems field less special: subscriptions are only added to the event list once they are fully initialised. Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: stable@vger.kernel.org # for 4.14 and up Fixes: c3b5b0241f62 ("V4L/DVB: V4L: Events: Add backend") Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/media')
-rw-r--r--include/media/v4l2-fh.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/media/v4l2-fh.h b/include/media/v4l2-fh.h
index 803516775162..4fdcd0d807d7 100644
--- a/include/media/v4l2-fh.h
+++ b/include/media/v4l2-fh.h
@@ -43,6 +43,7 @@ struct v4l2_fh {
wait_queue_head_t wait;
struct list_head subscribed; /* Subscribed events */
struct list_head available; /* Dequeueable event */
+ struct mutex subscribe_lock;
unsigned int navailable;
u32 sequence;