[Freeciv-Dev] (PR#11115) Unsafe use of create_server_list

["Benedict Adamson" <badamson@xxxxxxxxxxx>]

<URL: http://rt.freeciv.org/Ticket/Display.html?id=11115 >

The function create_server_list may return a NULL pointer. The 
get_meta_list function in client/gui-gtk-2.0/pages.c passes the value to 
update_server_list, which expects a non-NULL value.

In particular, it seems that a NULL value is possible if a DNS lookup of 
the meta server fails, which is very likely for a LAN without an 
Internet connection up.

This affects the latest development version and the latest beta release 
version.

Attached is a minimally tested patch.

--- vendor.freeciv.beta/client/gui-gtk-2.0/pages.c      2004-11-20 
17:15:24.000000000 +0000
+++ freeciv.PR10694-3/client/gui-gtk-2.0/pages.c        2004-11-21 
00:32:54.000000000 +0000
@@ -250,6 +250,7 @@
                               GtkListStore *store, struct server_list *list)
 {
   const gchar *host, *port;
+  assert(list);
 
   host = gtk_entry_get_text(GTK_ENTRY(network_host));
   port = gtk_entry_get_text(GTK_ENTRY(network_port));
@@ -286,9 +287,8 @@
 {
   struct server_list *server_list = create_server_list(errbuf, n_errbuf);
 
-  update_server_list(meta_selection, meta_store, server_list);
-
   if (server_list) {
+    update_server_list(meta_selection, meta_store, server_list);
     delete_server_list(server_list);
     return TRUE;
   } else {