[libxml2] Fix memory leak in xmlXIncludeAddNode error paths

[Nick Wellnhofer <nwellnhof src gnome org>]

commit fbb7fa9a9ad8269834d32ff872b1477ff7b9c705
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Wed Aug 19 13:13:20 2020 +0200

    Fix memory leak in xmlXIncludeAddNode error paths
    
    Found by OSS-Fuzz.

 xinclude.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)
---
diff --git a/xinclude.c b/xinclude.c
index 90245355e..aac30d5b0 100644
--- a/xinclude.c
+++ b/xinclude.c
@@ -627,8 +627,8 @@ xmlXIncludeAddNode(xmlXIncludeCtxtPtr ctxt, xmlNodePtr cur) {
        xmlXIncludeErr(ctxt, cur, XML_XINCLUDE_RECURSION,
                       "detected a local recursion with no xpointer in %s\n",
                       URL);
-       if (fragment != NULL)
-           xmlFree(fragment);
+        xmlFree(URL);
+        xmlFree(fragment);
        return(-1);
     }
 
@@ -640,12 +640,15 @@ xmlXIncludeAddNode(xmlXIncludeCtxtPtr ctxt, xmlNodePtr cur) {
            if (xmlStrEqual(URL, ctxt->urlTab[i])) {
                xmlXIncludeErr(ctxt, cur, XML_XINCLUDE_RECURSION,
                               "detected a recursion in %s\n", URL);
+                xmlFree(URL);
+                xmlFree(fragment);
                return(-1);
            }
        }
     }
 
     ref = xmlXIncludeNewRef(ctxt, URL, cur);
+    xmlFree(URL);
     if (ref == NULL) {
        return(-1);
     }
@@ -653,7 +656,6 @@ xmlXIncludeAddNode(xmlXIncludeCtxtPtr ctxt, xmlNodePtr cur) {
     ref->doc = NULL;
     ref->xml = xml;
     ref->count = 1;
-    xmlFree(URL);
     return(0);
 }