asfdec: free AVDictionaries properly when closing the demuxer

Signed-off-by: NAnton Khirnov <anton@khirnov.net>

libavformat/asfdec.c

@@ -1453,10 +1453,12 @@ static int asf_read_close(AVFormatContext *s)
     ASFContext *asf = s->priv_data;
     int i;
 
-    for (i = 0; i < asf->nb_streams; i++) {
-        av_free_packet(&asf->asf_st[i]->pkt.avpkt);
-        av_freep(&asf->asf_st[i]);
+    for (i = 0; i < ASF_MAX_STREAMS; i++) {
         av_dict_free(&asf->asf_sd[i].asf_met);
+        if (i < asf->nb_streams) {
+            av_free_packet(&asf->asf_st[i]->pkt.avpkt);
+            av_freep(&asf->asf_st[i]);
+        }
     }
 
     asf->nb_streams = 0;