From 8280b662df96f4172c4972b14a4aec0daf272b8f Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Tue, 6 Sep 2011 10:23:18 -0300 Subject: [PATCH] [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 Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/v4l2-dev.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c index 06f14008b346..d72156517726 100644 --- a/drivers/media/video/v4l2-dev.c +++ b/drivers/media/video/v4l2-dev.c @@ -173,6 +173,17 @@ static void v4l2_device_release(struct device *cd) 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);