Check for memory allocation failure of temp buffer

Originally committed as revision 11053 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/rmdec.c

@@ -495,7 +495,8 @@ static int rm_assemble_video_frame(AVFormatContext *s, RMContext *rm, AVPacket *
     if((seq & 0x7F) == 1 || rm->curpic_num != pic_num){
         rm->slices = ((hdr & 0x3F) << 1) + 1;
         ssize = len2 + 8*rm->slices + 1;
-        rm->videobuf = av_realloc(rm->videobuf, ssize);
+        if(!(rm->videobuf = av_realloc(rm->videobuf, ssize)))
+            return AVERROR(ENOMEM);
         rm->videobufsize = ssize;
         rm->videobufpos = 8*rm->slices + 1;
         rm->cur_slice = 0;