avformat/oggparsevorbis: Check that initialization succeeded before declaring the end of headers

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/oggparsevorbis.c

@@ -304,14 +304,14 @@ static int vorbis_header(AVFormatContext *s, int idx)
             return AVERROR(ENOMEM);
     }
 
+    priv = os->private;
+
     if (!(pkt_type & 1))
-        return 0;
+        return priv->vp ? 0 : AVERROR_INVALIDDATA;
 
     if (os->psize < 1 || pkt_type > 5)
         return AVERROR_INVALIDDATA;
 
-    priv = os->private;
-
     if (priv->packet[pkt_type >> 1])
         return AVERROR_INVALIDDATA;
     if (pkt_type > 1 && !priv->packet[0] || pkt_type > 3 && !priv->packet[1])