tmv: Check return value of avio_seek and avoid modifying state if it fails

Signed-off-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Justin Ruggles <justin.ruggles@gmail.com>

libavformat/tmv.c

@@ -174,7 +174,8 @@ static int tmv_read_seek(AVFormatContext *s, int stream_index,
     pos = timestamp *
           (tmv->audio_chunk_size + tmv->video_chunk_size + tmv->padding);
 
-    avio_seek(s->pb, pos + TMV_HEADER_SIZE, SEEK_SET);
+    if (avio_seek(s->pb, pos + TMV_HEADER_SIZE, SEEK_SET) < 0)
+        return -1;
     tmv->stream_index = 0;
     return 0;
 }