vb2: fix plane index sanity check in vb2_plane_cookie()

commit a9ae4692 upstream.

It's also invalid when plane_no is equal to vb->num_planes
Signed-off-by: Zhaowei Yuan <zhaowei.yuan@samsung.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/media/video/videobuf2-core.c

@@ -754,7 +754,7 @@ void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no)
 {
 	struct vb2_queue *q = vb->vb2_queue;
 
-	if (plane_no > vb->num_planes)
+	if (plane_no >= vb->num_planes)
 		return NULL;
 
 	return call_memop(q, plane_no, cookie, vb->planes[plane_no].mem_priv);