From 006c22233c5e68298c31b67f31b2959b679cdfaa Mon Sep 17 00:00:00 2001
From: Andrea Marchesini <amarchesini@mozilla.com>
Date: Thu, 4 Jun 2015 15:04:10 +0100
Subject: [PATCH] Bug 1167888 - better string length check in
 nsZipArchive::BuildFileList, r=smaug

---
 modules/libjar/nsZipArchive.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/modules/libjar/nsZipArchive.cpp b/modules/libjar/nsZipArchive.cpp
index 18b26e44c7b..507e1246539 100644
--- a/modules/libjar/nsZipArchive.cpp
+++ b/modules/libjar/nsZipArchive.cpp
@@ -644,8 +644,13 @@ MOZ_WIN_MEM_TRY_BEGIN
   if (!centralOffset)
     return NS_ERROR_FILE_CORRUPTED;
 
-  //-- Read the central directory headers
   buf = startp + centralOffset;
+
+  // avoid overflow of startp + centralOffset.
+  if (buf < startp)
+    return NS_ERROR_FILE_CORRUPTED;
+
+  //-- Read the central directory headers
   uint32_t sig = 0;
   while (buf + int32_t(sizeof(uint32_t)) <= endp &&
          (sig = xtolong(buf)) == CENTRALSIG) {