Fix XSS Vul for $invocation_user

Since the invocation id and invocation user cannot be anything but an alphanumeric string , we will use that check as our fix . This will avoid the usage of any JS code as values since it would need special chars like "<>"

portal/www/portal/sliceresource.php

@@ -62,6 +62,10 @@ function no_invocation_id_error() {
         array_key_exists("invocation_user", $_REQUEST)) {
     $invocation_user = $_REQUEST['invocation_user'];
     $invocation_id = $_REQUEST['invocation_id'];
+    if(!ctype_alnum($invocation_id) || !ctype_alnum($invocation_user))
+    {
+      relative_redirect('dashboard.php#slices');
+    }
 }
 else {
     no_invocation_id_error();