Hi Sakari, On 2017-04-07 04:40 AM, Sakari Ailus wrote:
Hi Helen, On Thu, Apr 06, 2017 at 04:32:00PM -0300, Helen Koike wrote:Fix kernel Oops NULL pointer deference Call dev_dbg_obj only after checking if gobj->mdev is not NULL Signed-off-by: Helen Koike <helen.koike@xxxxxxxxxxxxx> --- drivers/media/media-entity.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c index 5640ca2..bc44193 100644 --- a/drivers/media/media-entity.c +++ b/drivers/media/media-entity.c @@ -199,12 +199,12 @@ void media_gobj_create(struct media_device *mdev, void media_gobj_destroy(struct media_gobj *gobj) { - dev_dbg_obj(__func__, gobj); - /* Do nothing if the object is not linked. */ if (gobj->mdev == NULL) return; + dev_dbg_obj(__func__, gobj); + gobj->mdev->topology_version++; /* Remove the object from mdev list */Where is media_gobj_destroy() called with an object with NULL mdev? I do not object to the change, but would like to know because I don't think it's supposed to happen.
This happens when media_device_unregister(mdev) is called before unregistering the subdevices v4l2_device_unregister_subdev(sd) (which should be possible).
v4l2_device_unregister_subdev(sd) ends up calling v4l2_device_release() that calls media_device_unregister_entity() again (previously called by media_device_unregister(mdev)
Helen
There are issues though, until the patches fixing object referencing are finished and merged. Unfortunately I haven't been able to work on those recently, will pick them up again soon...
