[libxslt] Fix use-after-free in xsltDocumentFunctionLoadDocument

[Nick Wellnhofer <nwellnhof src gnome org>]

commit fc1ff481fd01e9a65a921c542fed68d8c965e8a3
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Thu Feb 25 17:16:06 2016 +0100

    Fix use-after-free in xsltDocumentFunctionLoadDocument
    
    Also fixes a memory leak in an unlikely error case.
    
    Fixes bug #758291
    https://bugzilla.gnome.org/show_bug.cgi?id=758291

 libxslt/functions.c         |    3 ++-
 tests/docs/bug-185-data.xml |    5 +++++
 tests/docs/bug-185.xml      |    2 ++
 tests/general/bug-185.err   |    3 +++
 tests/general/bug-185.xsl   |   14 ++++++++++++++
 5 files changed, 26 insertions(+), 1 deletions(-)
---
diff --git a/libxslt/functions.c b/libxslt/functions.c
index 549649c..a5e7021 100644
--- a/libxslt/functions.c
+++ b/libxslt/functions.c
@@ -180,7 +180,6 @@ xsltDocumentFunctionLoadDocument(xmlXPathParserContextPtr ctxt, xmlChar* URI)
     resObj = xmlXPtrEval(fragment, xptrctxt);
     xmlXPathFreeContext(xptrctxt);
 #endif
-    xmlFree(fragment);
 
     if (resObj == NULL)
        goto out_fragment;
@@ -204,6 +203,7 @@ xsltDocumentFunctionLoadDocument(xmlXPathParserContextPtr ctxt, xmlChar* URI)
     }
 
     valuePush(ctxt, resObj);
+    xmlFree(fragment);
     return;
 
 out_object:
@@ -211,6 +211,7 @@ out_object:
 
 out_fragment:
     valuePush(ctxt, xmlXPathNewNodeSet(NULL));
+    xmlFree(fragment);
 }
 
 /**
diff --git a/tests/docs/bug-185-data.xml b/tests/docs/bug-185-data.xml
new file mode 100644
index 0000000..166ef17
--- /dev/null
+++ b/tests/docs/bug-185-data.xml
@@ -0,0 +1,5 @@
+<!DOCTYPE test [ <!ATTLIST A id ID #REQUIRED> ] >
+<test>
+  <A id="X"/>
+  <A id="Y"/>
+</test>
diff --git a/tests/docs/bug-185.xml b/tests/docs/bug-185.xml
new file mode 100644
index 0000000..72bfdc4
--- /dev/null
+++ b/tests/docs/bug-185.xml
@@ -0,0 +1,2 @@
+<?xml-stylesheet href="poc.xsl" type="text/xsl"?>
+<in>bug-185-data.xml#xpointer(id('X')/range-to(id('Y')))</in>
diff --git a/tests/general/bug-185.err b/tests/general/bug-185.err
new file mode 100644
index 0000000..d7bbe92
--- /dev/null
+++ b/tests/general/bug-185.err
@@ -0,0 +1,3 @@
+runtime error: file ./bug-185.xsl line 7 element copy-of
+document() : XPointer does not select a node set: #xpointer(id('X')/range-to(id('Y')))
+no result for ./../docs/bug-185.xml
diff --git a/tests/general/bug-185.out b/tests/general/bug-185.out
new file mode 100644
index 0000000..e69de29
diff --git a/tests/general/bug-185.xsl b/tests/general/bug-185.xsl
new file mode 100644
index 0000000..1c5c7d1
--- /dev/null
+++ b/tests/general/bug-185.xsl
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"; version="1.0">
+  <xsl:template match="in">
+    <annotation>
+      <xsl:copy-of select="."/>
+      <value>
+        <xsl:copy-of select="document(.)"/>
+      </value>
+    </annotation>
+  </xsl:template>
+  <xsl:template match="@*|node()">
+    <xsl:apply-templates/>
+  </xsl:template>
+</xsl:stylesheet>