File expat-2.1.0-heap_buffer_overflow.patch of Package expat.23181

From ba0f9c3b40c264b8dd392e02a7a060a8fa54f032 Mon Sep 17 00:00:00 2001
From: Eric Rahm <erahm@mozilla.com>
Date: Wed, 2 Mar 2016 13:31:21 +0100
Subject: [PATCH] CVE-2015-1283 Sanity check size calculations. r=peterv,
 a=abillings

https://sourceforge.net/p/expat/bugs/528/
---
From f0bec73b018caa07d3e75ec8dd967f3785d71bde Mon Sep 17 00:00:00 2001
From: Pascal Cuoq <cuoq@trust-in-soft.com>
Date: Sun, 15 May 2016 09:05:46 +0200
Subject: [PATCH] Avoid relying on undefined behavior in CVE-2015-1283 fix. It
 does not really work: https://godbolt.org/g/Zl8gdF

---

Index: expat-2.1.0/lib/xmlparse.c
===================================================================
--- expat-2.1.0.orig/lib/xmlparse.c
+++ expat-2.1.0/lib/xmlparse.c
@@ -1678,6 +1678,10 @@ XML_ParseBuffer(XML_Parser parser, int l
 void * XMLCALL
 XML_GetBuffer(XML_Parser parser, int len)
 {
+  if (len < 0) {
+    errorCode = XML_ERROR_NO_MEMORY;
+    return NULL;
+  }
   switch (ps_parsing) {
   case XML_SUSPENDED:
     errorCode = XML_ERROR_SUSPENDED;
@@ -1689,8 +1693,12 @@ XML_GetBuffer(XML_Parser parser, int len
   }
 
   if (len > bufferLim - bufferEnd) {
-    /* FIXME avoid integer overflow */
-    int neededSize = len + (int)(bufferEnd - bufferPtr);
+    /* Do not invoke signed arithmetic overflow: */
+    int neededSize = (int) ((unsigned)len + (unsigned)(bufferEnd - bufferPtr));
+    if (neededSize < 0) {
+      errorCode = XML_ERROR_NO_MEMORY;
+      return NULL;
+    }
 #ifdef XML_CONTEXT_BYTES
     int keep = (int)(bufferPtr - buffer);
 
@@ -1718,8 +1726,13 @@ XML_GetBuffer(XML_Parser parser, int len
       if (bufferSize == 0)
         bufferSize = INIT_BUFFER_SIZE;
       do {
-        bufferSize *= 2;
-      } while (bufferSize < neededSize);
+        /* Do not invoke signed arithmetic overflow: */
+        bufferSize = (int) (2U * (unsigned) bufferSize);
+      } while (bufferSize < neededSize && bufferSize > 0);
+      if (bufferSize <= 0) {
+        errorCode = XML_ERROR_NO_MEMORY;
+        return NULL;
+      }
       newBuf = (char *)MALLOC(bufferSize);
       if (newBuf == 0) {
         errorCode = XML_ERROR_NO_MEMORY;