rmdec: dont return uninitialized data

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/rmdec.c

@@ -662,6 +662,7 @@ static int rm_assemble_video_frame(AVFormatContext *s, AVIOContext *pb,
     int hdr;
     int seq = 0, pic_num = 0, len2 = 0, pos = 0; //init to silcense compiler warning
     int type;
+    int ret;
 
     hdr = avio_r8(pb); len--;
     type = hdr >> 6;
@@ -690,7 +691,10 @@ static int rm_assemble_video_frame(AVFormatContext *s, AVIOContext *pb,
         pkt->data[0] = 0;
         AV_WL32(pkt->data + 1, 1);
         AV_WL32(pkt->data + 5, 0);
-        avio_read(pb, pkt->data + 9, len);
+        if ((ret = avio_read(pb, pkt->data + 9, len)) != len) {
+            av_free_packet(pkt);
+            return ret < 0 ? ret : AVERROR(EIO);
+        }
         return 0;
     }
     //now we have to deal with single slice
@@ -706,6 +710,7 @@ static int rm_assemble_video_frame(AVFormatContext *s, AVIOContext *pb,
         av_free_packet(&vst->pkt); //FIXME this should be output.
         if(av_new_packet(&vst->pkt, vst->videobufsize) < 0)
             return AVERROR(ENOMEM);
+        memset(vst->pkt.data, 0, vst->pkt.size);
         vst->videobufpos = 8*vst->slices + 1;
         vst->cur_slice = 0;
         vst->curpic_num = pic_num;