commit 316e730f1d8bb029fe6cec2468fb2a50424485b3 upstream. The topology that v4l2_m2m_register_media_controller() creates for a processing block actually created a source-to-source link and a sink-to-sink link instead of two source-to-sink links. Unfortunately v4l2-compliance never checked for such bad links, so this went unreported for quite some time. Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Reported-by: Nicolas Dufresne <nicolas@ndufresne.ca> Cc: <stable@vger.kernel.org> # for v4.19 and up Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>