matroska: check buffer size for RM-style byte reordering.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org

libavformat/matroskadec.c

@@ -1808,15 +1808,31 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, uint8_t *data,
                 if (!track->audio.pkt_cnt) {
                     if (track->audio.sub_packet_cnt == 0)
                         track->audio.buf_timecode = timecode;
-                    if (st->codec->codec_id == CODEC_ID_RA_288)
+                    if (st->codec->codec_id == CODEC_ID_RA_288) {
+                        if (size < cfs * h / 2) {
+                            av_log(matroska->ctx, AV_LOG_ERROR,
+                                   "Corrupt int4 RM-style audio packet size\n");
+                            return AVERROR_INVALIDDATA;
+                        }
                         for (x=0; x<h/2; x++)
                             memcpy(track->audio.buf+x*2*w+y*cfs,
                                    data+x*cfs, cfs);
-                    else if (st->codec->codec_id == CODEC_ID_SIPR)
+                    } else if (st->codec->codec_id == CODEC_ID_SIPR) {
+                        if (size < w) {
+                            av_log(matroska->ctx, AV_LOG_ERROR,
+                                   "Corrupt sipr RM-style audio packet size\n");
+                            return AVERROR_INVALIDDATA;
+                        }
                         memcpy(track->audio.buf + y*w, data, w);
-                    else
+                    } else {
+                        if (size < sps * w / sps) {
+                            av_log(matroska->ctx, AV_LOG_ERROR,
+                                   "Corrupt generic RM-style audio packet size\n");
+                            return AVERROR_INVALIDDATA;
+                        }
                         for (x=0; x<w/sps; x++)
                             memcpy(track->audio.buf+sps*(h*x+((h+1)/2)*(y&1)+(y>>1)), data+x*sps, sps);
+                    }
 
                     if (++track->audio.sub_packet_cnt >= h) {
                         if (st->codec->codec_id == CODEC_ID_SIPR)