media: uvcvideo: Also validate buffers in BULK mode

Just like for ISOC, validate the decoded BULK buffer size when possible.
This avoids sending corrupted or partial buffers to userspace, which may
lead to application crash or run-time failure.
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
[laurent.pinchart@ideasonboard.com: Move uvc_video_validate_buffer() call to uvc_video_next_buffers()]
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/usb/uvc/uvc_video.c

@@ -1232,6 +1232,8 @@ static void uvc_video_validate_buffer(const struct uvc_streaming *stream,
 static void uvc_video_next_buffers(struct uvc_streaming *stream,
 		struct uvc_buffer **video_buf, struct uvc_buffer **meta_buf)
 {
+	uvc_video_validate_buffer(stream, *video_buf);
+
 	if (*meta_buf) {
 		struct vb2_v4l2_buffer *vb2_meta = &(*meta_buf)->buf;
 		const struct vb2_v4l2_buffer *vb2_video = &(*video_buf)->buf;
@@ -1270,10 +1272,8 @@ static void uvc_video_decode_isoc(struct urb *urb, struct uvc_streaming *stream,
 		do {
 			ret = uvc_video_decode_start(stream, buf, mem,
 				urb->iso_frame_desc[i].actual_length);
-			if (ret == -EAGAIN) {
-				uvc_video_validate_buffer(stream, buf);
+			if (ret == -EAGAIN)
 				uvc_video_next_buffers(stream, &buf, &meta_buf);
-			}
 		} while (ret == -EAGAIN);
 
 		if (ret < 0)
@@ -1289,10 +1289,8 @@ static void uvc_video_decode_isoc(struct urb *urb, struct uvc_streaming *stream,
 		uvc_video_decode_end(stream, buf, mem,
 			urb->iso_frame_desc[i].actual_length);
 
-		if (buf->state == UVC_BUF_STATE_READY) {
-			uvc_video_validate_buffer(stream, buf);
+		if (buf->state == UVC_BUF_STATE_READY)
 			uvc_video_next_buffers(stream, &buf, &meta_buf);
-		}
 	}
 }