Merge commit '7bf96472'

* commit '7bf96472':
  vp7: bound checking in vp7_decode_frame_header

Only partially merged, see 46f72ea5Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>

libavcodec/vp8.c

@@ -493,6 +493,10 @@ static int vp7_decode_frame_header(VP8Context *s, const uint8_t *buf, int buf_si
     int width  = s->avctx->width;
     int height = s->avctx->height;
 
+    if (buf_size < 4) {
+        return AVERROR_INVALIDDATA;
+    }
+
     s->profile = (buf[0] >> 1) & 7;
     if (s->profile > 1) {
         avpriv_request_sample(s->avctx, "Unknown profile %d", s->profile);