Index: smbd/password.c
===================================================================
--- smbd/password.c	(revision 484)
+++ smbd/password.c	(working copy)
@@ -488,7 +488,11 @@
 	/* now check the list of session users */
 	if (!ok) {
 		char *auser;
-		char *user_list = strdup(session_userlist);
+		char *user_list = NULL;
+
+		if ( session_userlist )
+			user_list = strdup(session_userlist);
+
 		if (!user_list)
 			return(False);