https://www.illumos.org/issues/4319

--- libgksu-2.0.12/libgksu/libgksu.c.orig	2014-04-02 23:37:47.377394439 +0400
+++ libgksu-2.0.12/libgksu/libgksu.c	2014-04-02 23:39:38.674104554 +0400
@@ -1628,7 +1628,9 @@
 
   for ( i = 0; i<context->msg_num; i++ ) {
        g_free (context->pam_message[i].msg);
-       g_free (context->pam_response[i].resp);
+       if(context->pam_response) {
+         g_free (context->pam_response[i].resp);
+       }
   }
   g_free (context->pam_message);
   g_free (context->pam_response);