This patch addresses two heap overflow bugs in raptor2:

http://seclists.org/oss-sec/2017/q2/424

Patch copied from libreoffice:

https://github.com/LibreOffice/core/blob/master/external/redland/raptor/0001-Calcualte-max-nspace-declarations-correctly-for-XML-.patch.1

From 590681e546cd9aa18d57dc2ea1858cb734a3863f Mon Sep 17 00:00:00 2001
From: Dave Beckett <dave@dajobe.org>
Date: Sun, 16 Apr 2017 23:15:12 +0100
Subject: [PATCH] Calcualte max nspace declarations correctly for XML writer

(raptor_xml_writer_start_element_common): Calculate max including for
each attribute a potential name and value.

Fixes Issues #0000617 http://bugs.librdf.org/mantis/view.php?id=617
and #0000618 http://bugs.librdf.org/mantis/view.php?id=618
---
 src/raptor_xml_writer.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/raptor_xml_writer.c b/src/raptor_xml_writer.c
index 693b946..0d3a36a 100644
--- a/src/raptor_xml_writer.c
+++ b/src/raptor_xml_writer.c
@@ -181,9 +181,10 @@ raptor_xml_writer_start_element_common(raptor_xml_writer* xml_writer,
   size_t nspace_declarations_count = 0;  
   unsigned int i;
 
-  /* max is 1 per element and 1 for each attribute + size of declared */
   if(nstack) {
-    int nspace_max_count = element->attribute_count+1;
+    int nspace_max_count = element->attribute_count * 2; /* attr and value */
+    if(element->name->nspace)
+      nspace_max_count++;
     if(element->declared_nspaces)
       nspace_max_count += raptor_sequence_size(element->declared_nspaces);
     if(element->xml_language)
@@ -237,7 +238,7 @@ raptor_xml_writer_start_element_common(raptor_xml_writer* xml_writer,
         }
       }
 
-      /* Add the attribute + value */
+      /* Add the attribute's value */
       nspace_declarations[nspace_declarations_count].declaration=
         raptor_qname_format_as_xml(element->attributes[i],
                                    &nspace_declarations[nspace_declarations_count].length);
-- 
2.9.3

