From: Pi-Hsun Shih pihsun@chromium.org
[ Upstream commit df4a3e7f88e3b0d7ae46d70b9ff8e3c0ea730785 ]
There's a race condition between the list_del_init in the v4l2_ctrl_request_complete, and the list_add_tail in the v4l2_ctrl_request_queue, since they can be called in different thread and the requests_queued list is not protected by a lock. This can lead to that the v4l2_ctrl_handler is still in the requests_queued list while the request_is_queued is already set to false, which would cause use-after-free if the v4l2_ctrl_handler is later released.
Fix this by locking the ->lock of main_hdl (which is the owner of the requests_queued list) when doing list operations on the ->requests_queued list.
Signed-off-by: Pi-Hsun Shih pihsun@chromium.org Signed-off-by: Hans Verkuil hverkuil-cisco@xs4all.nl Signed-off-by: Mauro Carvalho Chehab mchehab@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/media/v4l2-core/v4l2-ctrls.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c index 1d8f388246313..cd84dbbf6a890 100644 --- a/drivers/media/v4l2-core/v4l2-ctrls.c +++ b/drivers/media/v4l2-core/v4l2-ctrls.c @@ -3144,6 +3144,7 @@ static void v4l2_ctrl_request_queue(struct media_request_object *obj) struct v4l2_ctrl_handler *prev_hdl = NULL; struct v4l2_ctrl_ref *ref_ctrl, *ref_ctrl_prev = NULL;
+ mutex_lock(main_hdl->lock); if (list_empty(&main_hdl->requests_queued)) goto queue;
@@ -3175,18 +3176,22 @@ static void v4l2_ctrl_request_queue(struct media_request_object *obj) queue: list_add_tail(&hdl->requests_queued, &main_hdl->requests_queued); hdl->request_is_queued = true; + mutex_unlock(main_hdl->lock); }
static void v4l2_ctrl_request_unbind(struct media_request_object *obj) { struct v4l2_ctrl_handler *hdl = container_of(obj, struct v4l2_ctrl_handler, req_obj); + struct v4l2_ctrl_handler *main_hdl = obj->priv;
list_del_init(&hdl->requests); + mutex_lock(main_hdl->lock); if (hdl->request_is_queued) { list_del_init(&hdl->requests_queued); hdl->request_is_queued = false; } + mutex_unlock(main_hdl->lock); }
static void v4l2_ctrl_request_release(struct media_request_object *obj) @@ -4128,9 +4133,11 @@ void v4l2_ctrl_request_complete(struct media_request *req, v4l2_ctrl_unlock(ctrl); }
+ mutex_lock(main_hdl->lock); WARN_ON(!hdl->request_is_queued); list_del_init(&hdl->requests_queued); hdl->request_is_queued = false; + mutex_unlock(main_hdl->lock); media_request_object_complete(obj); media_request_object_put(obj); }