Properly cleanup XML parser contexts upon completion

It is currently possible that the XML parsing context is not properly
cleaned up if a parsed XML document is malformed.

This fix makes sure that the context is taken care of.

Signed-off-by: Vladimir Krivopalov <vlkrivop@microsoft.com>

Author: vkrivopalov

apache2/msc_xml.c

@@ -137,6 +137,13 @@ int xml_complete(modsec_rec *msr, char **error_msg) {
  * Frees the resources used for XML parsing.
  */
 apr_status_t xml_cleanup(modsec_rec *msr) {
+    if (msr->xml->parsing_ctx != NULL) {
+        if (msr->xml->parsing_ctx->myDoc) {
+            xmlFreeDoc(msr->xml->parsing_ctx->myDoc);
+        }
+        xmlFreeParserCtxt(msr->xml->parsing_ctx);
+        msr->xml->parsing_ctx = NULL;
+    }
     if (msr->xml->doc != NULL) {
         xmlFreeDoc(msr->xml->doc);
         msr->xml->doc = NULL;