TTA : Check if the output buffer size is within bounds.

Fixes issue 1848.

Originally committed as revision 22711 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/tta.c

@@ -302,6 +302,10 @@ static int tta_decode_frame(AVCodecContext *avctx,
         int cur_chan = 0, framelen = s->frame_length;
         int32_t *p;
 
+        if (*data_size < (framelen * s->channels * 2)) {
+            av_log(avctx, AV_LOG_ERROR,"Output buffer size is too small.\n");
+            return -1;
+        }
         // FIXME: seeking
         s->total_frames--;
         if (!s->total_frames && s->last_frame_length)