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| author | Sakari Ailus <sakari.ailus@linux.intel.com> | 2018-09-11 05:32:37 -0400 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2018-10-03 06:32:51 -0400 |
| commit | ad608fbcf166fec809e402d548761768f602702c (patch) | |
| tree | 7c0b71ffee7dfb6a03ba25afb532c7af732eaa4e /include | |
| parent | 324493fba77500592bbaa66421729421f139d4b5 (diff) | |
| download | linux-ad608fbcf166fec809e402d548761768f602702c.tar.bz2 | |
media: v4l: event: Prevent freeing event subscriptions while accessed
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>
Diffstat (limited to 'include')
| -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 ea73fef8bdc0..8586cfb49828 100644 --- a/include/media/v4l2-fh.h +++ b/include/media/v4l2-fh.h @@ -38,10 +38,13 @@ 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 { @@ -52,6 +55,7 @@ struct v4l2_fh { /* Events */ wait_queue_head_t wait; + struct mutex subscribe_lock; struct list_head subscribed; struct list_head available; unsigned int navailable; |