diff options
author | Sakari Ailus <sakari.ailus@linux.intel.com> | 2018-09-11 12:32:37 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-10-04 03:01:00 +0300 |
commit | d61ba3417e4fb71963441aa0c2e9c26f4568215b (patch) | |
tree | 6a209cb823ce7644d6f39da1ac63038f0d28e35a /include/media | |
parent | fcaca557760f4fd78e793d8bfc4364fb58d7fb85 (diff) | |
download | linux-d61ba3417e4fb71963441aa0c2e9c26f4568215b.tar.xz |
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.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/media/v4l2-fh.h b/include/media/v4l2-fh.h index 62633e7d2630..0f22a5eda4cc 100644 --- a/include/media/v4l2-fh.h +++ b/include/media/v4l2-fh.h @@ -37,10 +37,13 @@ struct v4l2_ctrl_handler; * @prio: priority of the file handler, as defined by &enum v4l2_priority * * @wait: event' s wait queue + * @subscribe_lock: serialise changes to the subscribed list; guarantee that + * the add and del event callbacks are orderly called * @subscribed: list of subscribed events * @available: list of events waiting to be dequeued * @navailable: number of available events at @available list * @sequence: event sequence number + * * @m2m_ctx: pointer to &struct v4l2_m2m_ctx */ struct v4l2_fh { @@ -51,6 +54,7 @@ struct v4l2_fh { /* Events */ wait_queue_head_t wait; + struct mutex subscribe_lock; struct list_head subscribed; struct list_head available; unsigned int navailable; |