This is a note to let you know that I've just added the patch titled
[media] v4l: vsp1: Prevent multiple streamon race commencing pipeline early
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: v4l-vsp1-prevent-multiple-streamon-race-commencing-pipeline-early.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Sun Mar 18 16:55:33 CET 2018
From: Kieran Bingham kieran.bingham+renesas@ideasonboard.com Date: Fri, 6 Jan 2017 10:15:28 -0200 Subject: [media] v4l: vsp1: Prevent multiple streamon race commencing pipeline early
From: Kieran Bingham kieran.bingham+renesas@ideasonboard.com
[ Upstream commit 4461c84b52b4a952c657505ef7e4e06b016783df ]
With multiple inputs through the BRU it is feasible for the streams to race each other at stream-on.
Multiple VIDIOC_STREAMON calls racing each other could have process N-1 skipping over the pipeline setup section and then start the pipeline early, if videobuf2 has already enqueued buffers to the driver for process N but not called the .start_streaming() operation yet
In the case of the video pipelines, this can present two serious issues.
1) A null-dereference if the pipe->dl is committed at the same time as the vsp1_video_setup_pipeline() is processing
2) A hardware hang, where a display list is committed without having called vsp1_video_setup_pipeline() first
Repair this issue, by ensuring that only the stream which configures the pipeline is able to start it.
Signed-off-by: Kieran Bingham kieran.bingham+renesas@ideasonboard.com Reviewed-by: Laurent Pinchart laurent.pinchart+renesas@ideasonboard.com Signed-off-by: Mauro Carvalho Chehab mchehab@s-opensource.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/media/platform/vsp1/vsp1_video.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
--- a/drivers/media/platform/vsp1/vsp1_video.c +++ b/drivers/media/platform/vsp1/vsp1_video.c @@ -792,6 +792,7 @@ static int vsp1_video_start_streaming(st { struct vsp1_video *video = vb2_get_drv_priv(vq); struct vsp1_pipeline *pipe = video->rwpf->pipe; + bool start_pipeline = false; unsigned long flags; int ret;
@@ -802,11 +803,23 @@ static int vsp1_video_start_streaming(st mutex_unlock(&pipe->lock); return ret; } + + start_pipeline = true; }
pipe->stream_count++; mutex_unlock(&pipe->lock);
+ /* + * vsp1_pipeline_ready() is not sufficient to establish that all streams + * are prepared and the pipeline is configured, as multiple streams + * can race through streamon with buffers already queued; Therefore we + * don't even attempt to start the pipeline until the last stream has + * called through here. + */ + if (!start_pipeline) + return 0; + spin_lock_irqsave(&pipe->irqlock, flags); if (vsp1_pipeline_ready(pipe)) vsp1_video_pipeline_run(pipe);
Patches currently in stable-queue which might be from kieran.bingham+renesas@ideasonboard.com are
queue-4.9/v4l-vsp1-prevent-multiple-streamon-race-commencing-pipeline-early.patch queue-4.9/v4l-vsp1-register-pipe-with-output-wpf.patch queue-4.9/media-vsp1-prevent-suspending-and-resuming-drm-pipelines.patch