4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Kieran Bingham <[email protected]> [ 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 <[email protected]> Reviewed-by: Laurent Pinchart <[email protected]> Signed-off-by: Mauro Carvalho Chehab <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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);
