media: usbtv: Lock resolution while streaming

When an program is streaming (ffplay) and another program (qv4l2)
changes the TV standard from NTSC to PAL, the kernel crashes due to trying
to copy to unmapped memory.

Changing from NTSC to PAL increases the resolution in the usbtv struct,
but the video plane buffer isn't adjusted, so it overflows.

Fixes: 0e0fe3958fdd13d ("[media] usbtv: Add support for PAL video source")
Cc: stable@vger.kernel.org
Signed-off-by: Ludwig Disterhof <ludwig@disterhof.eu>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
[hverkuil: call vb2_is_busy instead of vb2_is_streaming]

diff --git a/drivers/media/usb/usbtv/usbtv-video.c b/drivers/media/usb/usbtv/usbtv-video.c
index be22a9697197c6078981a84b882ec85cd591506c..de0328100a60dd7b4335e208fee4cd2864d5b99d 100644 (file)
--- a/drivers/media/usb/usbtv/usbtv-video.c
+++ b/drivers/media/usb/usbtv/usbtv-video.c
@@ -73,6 +73,10 @@ static int usbtv_configure_for_norm(struct usbtv *usbtv, v4l2_std_id norm)
        }
 
        if (params) {
+               if (vb2_is_busy(&usbtv->vb2q) &&
+                   (usbtv->width != params->cap_width ||
+                    usbtv->height != params->cap_height))
+                       return -EBUSY;
                usbtv->width = params->cap_width;
                usbtv->height = params->cap_height;
                usbtv->n_chunks = usbtv->width * usbtv->height