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From ab22e3a00f04b458039c21111cfa448051e5777d Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Thu, 3 Jan 2019 12:59:28 +0100
Subject: [PATCH] ntlm: fix *_type3_message size check to avoid buffer overflow

Bug: https://curl.haxx.se/docs/CVE-2019-3822.html
Reported-by: Wenxiang Qian
CVE-2019-3822

Upstream-commit: 50c9484278c63b958655a717844f0721263939cc
Signed-off-by: Kamil Dudka <kdudka@redhat.com>
---
 lib/vauth/ntlm.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/lib/vauth/ntlm.c b/lib/vauth/ntlm.c
index b614cda..a3a55d9 100644
--- a/lib/vauth/ntlm.c
+++ b/lib/vauth/ntlm.c
@@ -777,11 +777,14 @@ CURLcode Curl_auth_create_ntlm_type3_message(struct Curl_easy *data,
   });
 
 #ifdef USE_NTRESPONSES
-  if(size < (NTLM_BUFSIZE - ntresplen)) {
-    DEBUGASSERT(size == (size_t)ntrespoff);
-    memcpy(&ntlmbuf[size], ptr_ntresp, ntresplen);
-    size += ntresplen;
+  /* ntresplen + size should not be risking an integer overflow here */
+  if(ntresplen + size > sizeof(ntlmbuf)) {
+    failf(data, "incoming NTLM message too big");
+    return CURLE_OUT_OF_MEMORY;
   }
+  DEBUGASSERT(size == (size_t)ntrespoff);
+  memcpy(&ntlmbuf[size], ptr_ntresp, ntresplen);
+  size += ntresplen;
 
   DEBUG_OUT({
     fprintf(stderr, "\n   ntresp=");
-- 
2.17.2