[media] vb2: fix handling of data_offset and v4l2_plane.reserved[]

The videobuf2-core did not zero the 'planes' array in __qbuf_userptr()
and __qbuf_dmabuf(). That's now memset to 0. Without this the reserved
array in struct v4l2_plane would be non-zero, causing v4l2-compliance
errors.

More serious is the fact that data_offset was not handled correctly:

- for capture devices it was never zeroed, which meant that it was
  uninitialized. Unless the driver sets it it was a completely random
  number. With the memset above this is now fixed.

- __qbuf_dmabuf had a completely incorrect length check that included
  data_offset.

- in __fill_vb2_buffer in the DMABUF case the data_offset field was
  unconditionally copied from v4l2_buffer to v4l2_plane when this
  should only happen in the output case.

- in the single-planar case data_offset was never correctly set to 0.
  The single-planar API doesn't support data_offset, so setting it
  to 0 is the right thing to do. This too is now solved by the memset.

All these issues were found with v4l2-compliance.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Pawel Osciak <pawel@osciak.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/v4l2-core/videobuf2-core.c

@@ -1234,8 +1234,6 @@ static void __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b
 					b->m.planes[plane].m.fd;
 				v4l2_planes[plane].length =
 					b->m.planes[plane].length;
-				v4l2_planes[plane].data_offset =
-					b->m.planes[plane].data_offset;
 			}
 		}
 	} else {
@@ -1245,10 +1243,8 @@ static void __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b
 		 * In videobuf we use our internal V4l2_planes struct for
 		 * single-planar buffers as well, for simplicity.
 		 */
-		if (V4L2_TYPE_IS_OUTPUT(b->type)) {
+		if (V4L2_TYPE_IS_OUTPUT(b->type))
 			v4l2_planes[0].bytesused = b->bytesused;
-			v4l2_planes[0].data_offset = 0;
-		}
 
 		if (b->memory == V4L2_MEMORY_USERPTR) {
 			v4l2_planes[0].m.userptr = b->m.userptr;
@@ -1258,9 +1254,7 @@ static void __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b
 		if (b->memory == V4L2_MEMORY_DMABUF) {
 			v4l2_planes[0].m.fd = b->m.fd;
 			v4l2_planes[0].length = b->length;
-			v4l2_planes[0].data_offset = 0;
 		}
-
 	}
 
 	/* Zero flags that the vb2 core handles */
@@ -1303,6 +1297,7 @@ static int __qbuf_userptr(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 	int write = !V4L2_TYPE_IS_OUTPUT(q->type);
 	bool reacquired = vb->planes[0].mem_priv == NULL;
 
+	memset(planes, 0, sizeof(planes[0]) * vb->num_planes);
 	/* Copy relevant information provided by the userspace */
 	__fill_vb2_buffer(vb, b, planes);
 
@@ -1414,6 +1409,7 @@ static int __qbuf_dmabuf(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 	int write = !V4L2_TYPE_IS_OUTPUT(q->type);
 	bool reacquired = vb->planes[0].mem_priv == NULL;
 
+	memset(planes, 0, sizeof(planes[0]) * vb->num_planes);
 	/* Copy relevant information provided by the userspace */
 	__fill_vb2_buffer(vb, b, planes);
 
@@ -1431,8 +1427,7 @@ static int __qbuf_dmabuf(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 		if (planes[plane].length == 0)
 			planes[plane].length = dbuf->size;
 
-		if (planes[plane].length < planes[plane].data_offset +
-		    q->plane_sizes[plane]) {
+		if (planes[plane].length < q->plane_sizes[plane]) {
 			dprintk(1, "qbuf: invalid dmabuf length for plane %d\n",
 				plane);
 			ret = -EINVAL;