Vorbis specs requires blocksize_1 >= blocksize_0, error if it's false.

Predict buffer size from blocksize_1 and number of channels and make
sure this does not exceed AVCODEC_MAX_AUDIO_FRAME_SIZE

Patch by Uoti Urpala >>> uoti |.| urpala |@| pp1 |.| inet |.| fi <<<

Originally committed as revision 5313 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/vorbis.c

@@ -872,10 +872,17 @@ static int vorbis_parse_id_hdr(vorbis_context *vc){
     bl1=get_bits(gb, 4);
     vc->blocksize_0=(1<<bl0);
     vc->blocksize_1=(1<<bl1);
-    if (bl0>13 || bl0<6 || bl1>13 || bl1<6) {
+    if (bl0>13 || bl0<6 || bl1>13 || bl1<6 || bl1<bl0) {
         av_log(vc->avccontext, AV_LOG_ERROR, " Vorbis id header packet corrupt (illegal blocksize). \n");
         return 3;
     }
+    // output format int16
+    if (vc->blocksize_1/2 * vc->audio_channels * 2 >
+                                             AVCODEC_MAX_AUDIO_FRAME_SIZE) {
+        av_log(vc->avccontext, AV_LOG_ERROR, "Vorbis channel count makes "
+               "output packets too large.\n");
+        return 4;
+    }
     vc->swin=vwin[bl0-6];
     vc->lwin=vwin[bl1-6];