NTLM: fix size check condition for type2 received data

Bug: https://curl.haxx.se/docs/CVE-2018-16890.html
Reported-by: Wenxiang Qian
CVE-2018-16890

lib/vauth/ntlm.c

@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -182,10 +182,11 @@ static CURLcode ntlm_decode_type2_target(struct Curl_easy *data,
     target_info_len = Curl_read16_le(&buffer[40]);
     target_info_offset = Curl_read32_le(&buffer[44]);
     if(target_info_len > 0) {
-      if(((target_info_offset + target_info_len) > size) ||
+      if((target_info_offset >= size) ||
+         ((target_info_offset + target_info_len) > size) ||
          (target_info_offset < 48)) {
         infof(data, "NTLM handshake failure (bad type-2 message). "
-                    "Target Info Offset Len is set incorrect by the peer\n");
+              "Target Info Offset Len is set incorrect by the peer\n");
         return CURLE_BAD_CONTENT_ENCODING;
       }