[PATCH] v4l/bttv: add sanity check (bug #3309)

Missing sanity check, overlay is supported for packed pixel formats only.
Patch below.  It's not API related btw, the bug can be triggered using the
v4l2 API as well.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/media/video/bttv-driver.c

@@ -1861,6 +1861,8 @@ static int setup_window(struct bttv_fh *fh, struct bttv *btv,
 
 	if (NULL == fh->ovfmt)
 		return -EINVAL;
+	if (!(fh->ovfmt->flags & FORMAT_FLAGS_PACKED))
+		return -EINVAL;
 	retval = verify_window(&bttv_tvnorms[btv->tvnorm],win,fixup);
 	if (0 != retval)
 		return retval;