media: v4l2-dv-timings: add sanity checks for blanking values

Add sanity checks to v4l2_valid_dv_timings() to ensure that the provided
blanking values are reasonable.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Fixes: b18787e ([media] v4l2-dv-timings: add new helper module)
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/v4l2-core/v4l2-dv-timings.c

@@ -161,6 +161,20 @@ bool v4l2_valid_dv_timings(const struct v4l2_dv_timings *t,
 	    (bt->interlaced && !(caps & V4L2_DV_BT_CAP_INTERLACED)) ||
 	    (!bt->interlaced && !(caps & V4L2_DV_BT_CAP_PROGRESSIVE)))
 		return false;
+
+	/* sanity checks for the blanking timings */
+	if (!bt->interlaced &&
+	    (bt->il_vbackporch || bt->il_vsync || bt->il_vfrontporch))
+		return false;
+	if (bt->hfrontporch > 2 * bt->width ||
+	    bt->hsync > 1024 || bt->hbackporch > 1024)
+		return false;
+	if (bt->vfrontporch > 4096 ||
+	    bt->vsync > 128 || bt->vbackporch > 4096)
+		return false;
+	if (bt->interlaced && (bt->il_vfrontporch > 4096 ||
+	    bt->il_vsync > 128 || bt->il_vbackporch > 4096))
+		return false;
 	return fnc == NULL || fnc(t, fnc_handle);
 }
 EXPORT_SYMBOL_GPL(v4l2_valid_dv_timings);