avformat/sierravmd: check for memory allocation failures

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavformat/sierravmd.c

@@ -126,8 +126,10 @@ static int vmd_read_header(AVFormatContext *s)
             vst->codec->width >>= 1;
             vst->codec->height >>= 1;
         }
-        vst->codec->extradata_size = VMD_HEADER_SIZE;
         vst->codec->extradata = av_mallocz(VMD_HEADER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE);
+        if (!vst->codec->extradata)
+            return AVERROR(ENOMEM);
+        vst->codec->extradata_size = VMD_HEADER_SIZE;
         memcpy(vst->codec->extradata, vmd->vmd_header, VMD_HEADER_SIZE);
     }