From 8524cb8b7b377ff6acb1ca51afc7255d02c4170b Mon Sep 17 00:00:00 2001
From: Sadaf Ebrahimi <sadafebrahimi@google.com>
Date: Fri, 3 Jun 2022 03:40:21 +0000
Subject: Prevent integer overflow in function doProlog

Bug: http://b/221256678
Change-Id: I6fe381103f4eb287726d1ccb5bfec99db160ffe4
---
 lib/xmlparse.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/lib/xmlparse.c b/lib/xmlparse.c
index 3aaf35b9..09b1997d 100644
--- a/lib/xmlparse.c
+++ b/lib/xmlparse.c
@@ -4972,7 +4972,7 @@ doProlog(XML_Parser parser, const ENCODING *enc, const char *s, const char *end,
       if (dtd->in_eldecl) {
         ELEMENT_TYPE *el;
         const XML_Char *name;
-        int nameLen;
+        size_t nameLen;
         const char *nxt
             = (quant == XML_CQUANT_NONE ? next : next - enc->minBytesPerChar);
         int myindex = nextScaffoldPart(parser);
@@ -4988,7 +4988,13 @@ doProlog(XML_Parser parser, const ENCODING *enc, const char *s, const char *end,
         nameLen = 0;
         for (; name[nameLen++];)
           ;
-        dtd->contentStringLen += nameLen;
+
+        /* Detect and prevent integer overflow */
+        if (nameLen > UINT_MAX - dtd->contentStringLen) {
+          return XML_ERROR_NO_MEMORY;
+        }
+
+        dtd->contentStringLen += (unsigned)nameLen;
         if (parser->m_elementDeclHandler)
           handleDefault = XML_FALSE;
       }
-- 
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