[media] v4l: Fix use-after-free case in v4l2_device_release
Drivers that have no v4l2_device release callback might free the
v4l2_device instance in the video_device release callback. Make sure we
don't access the v4l2_device instance after it gets freed.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index 06f1400..d721565 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -173,6 +173,17 @@
media_device_unregister_entity(&vdev->entity);
#endif
+ /* Do not call v4l2_device_put if there is no release callback set.
+ * Drivers that have no v4l2_device release callback might free the
+ * v4l2_dev instance in the video_device release callback below, so we
+ * must perform this check here.
+ *
+ * TODO: In the long run all drivers that use v4l2_device should use the
+ * v4l2_device release callback. This check will then be unnecessary.
+ */
+ if (v4l2_dev->release == NULL)
+ v4l2_dev = NULL;
+
/* Release video_device and perform other
cleanups as needed. */
vdev->release(vdev);