Initilising these variables before appending the domain groups to them

source/rpc_server/srv_netlog_nt.c

@@ -637,7 +637,9 @@ NTSTATUS _net_sam_logon(pipes_struct *p, NET_Q_SAM_LOGON *q_u, NET_R_SAM_LOGON *
 		 * rids and then into machine sids for this user.
 		 * JRA.
 		 */
-        
+
+		*domain_groups = 0;
+  
 		get_domain_user_groups(domain_groups, nt_username);
         
 		/*

source/rpc_server/srv_samr_nt.c

@@ -1833,6 +1833,8 @@ NTSTATUS _samr_query_usergroups(pipes_struct *p, SAMR_Q_QUERY_USERGROUPS *q_u, S
 		return NT_STATUS_NO_SUCH_USER;
 	}
 
+	*groups = 0;
+
 	get_domain_user_groups(groups, pdb_get_username(sam_pass));
 	gids = NULL;
 	num_groups = make_dom_gids(p->mem_ctx, groups, &gids);