media: v4l2-ctrl: Validate VP8 stateless decoder controls

Only one field needs to be validated: 'num_dct_parts'.
This field is used to iterate over the user-provided array
'dct_part_sizes'.
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
[hverkuil-cisco@xs4all.nl: s -> (s) in zero_padding macro]
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

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

@@ -1633,10 +1633,15 @@ static void std_log(const struct v4l2_ctrl *ctrl)
 })
 
 /* Validate a new control */
+
+#define zero_padding(s) \
+	memset(&(s).padding, 0, sizeof((s).padding))
+
 static int std_validate_compound(const struct v4l2_ctrl *ctrl, u32 idx,
 				 union v4l2_ctrl_ptr ptr)
 {
 	struct v4l2_ctrl_mpeg2_slice_params *p_mpeg2_slice_params;
+	struct v4l2_ctrl_vp8_frame_header *p_vp8_frame_header;
 	void *p = ptr.p + idx * ctrl->elem_size;
 
 	switch ((u32)ctrl->type) {
@@ -1696,6 +1701,22 @@ static int std_validate_compound(const struct v4l2_ctrl *ctrl, u32 idx,
 		break;
 
 	case V4L2_CTRL_TYPE_VP8_FRAME_HEADER:
+		p_vp8_frame_header = p;
+
+		switch (p_vp8_frame_header->num_dct_parts) {
+		case 1:
+		case 2:
+		case 4:
+		case 8:
+			break;
+		default:
+			return -EINVAL;
+		}
+		zero_padding(p_vp8_frame_header->segment_header);
+		zero_padding(p_vp8_frame_header->lf_header);
+		zero_padding(p_vp8_frame_header->quant_header);
+		zero_padding(p_vp8_frame_header->entropy_header);
+		zero_padding(p_vp8_frame_header->coder_state);
 		break;
 	default:
 		return -EINVAL;