[media] videobuf2-core: Check user space planes array in dqbuf

The number of planes in videobuf2 is specific to a buffer. In order to
verify that the planes array provided by the user is long enough, a new
vb2_buf_op is required.

Call __verify_planes_array() when the dequeued buffer is known. Return an
error to the caller if there was one, otherwise remove the buffer from the
done list.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: stable@vger.kernel.org # for v4.4 and later
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

include/media/videobuf2-core.h

@@ -375,6 +375,9 @@ struct vb2_ops {
 /**
  * struct vb2_ops - driver-specific callbacks
  *
+ * @verify_planes_array: Verify that a given user space structure contains
+ *			enough planes for the buffer. This is called
+ *			for each dequeued buffer.
  * @fill_user_buffer:	given a vb2_buffer fill in the userspace structure.
  *			For V4L2 this is a struct v4l2_buffer.
  * @fill_vb2_buffer:	given a userspace structure, fill in the vb2_buffer.
@@ -384,6 +387,7 @@ struct vb2_ops {
  *			the vb2_buffer struct.
  */
 struct vb2_buf_ops {
+	int (*verify_planes_array)(struct vb2_buffer *vb, const void *pb);
 	void (*fill_user_buffer)(struct vb2_buffer *vb, void *pb);
 	int (*fill_vb2_buffer)(struct vb2_buffer *vb, const void *pb,
 				struct vb2_plane *planes);