From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Sadaf Ebrahimi <sadafebrahimi@google.com>
Date: Thu, 2 Jun 2022 19:32:22 +0000
Subject: [PATCH] Prevent XML_GetBuffer signed integer overflow

Bug: http://b/221255869
Change-Id: I38758fae8c71184f728f95e6073457cdb86bcc29
(cherry picked from commit d6a09f1b7fb24dd03dc58e45062ad951a37ff8e3)
Merged-In: I38758fae8c71184f728f95e6073457cdb86bcc29
---
 lib/xmlparse.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/xmlparse.c b/lib/xmlparse.c
index 67f661b5..1d6e722d 100644
--- a/lib/xmlparse.c
+++ b/lib/xmlparse.c
@@ -2040,6 +2040,11 @@ XML_GetBuffer(XML_Parser parser, int len)
     keep = (int)(parser->m_bufferPtr - parser->m_buffer);
     if (keep > XML_CONTEXT_BYTES)
       keep = XML_CONTEXT_BYTES;
+    /* Detect and prevent integer overflow */
+    if (keep > INT_MAX - neededSize) {
+      parser->m_errorCode = XML_ERROR_NO_MEMORY;
+      return NULL;
+    }
     neededSize += keep;
 #endif  /* defined XML_CONTEXT_BYTES */
     if (neededSize  <= parser->m_bufferLim - parser->m_buffer) {