[gdm] slave: check object path validity before creating proxy from it

[Ray Strode <halfline src gnome org>]

commit fdc2668769bfddaec19ffd174b9c9c97caeb61f8
Author: Ray Strode <rstrode redhat com>
Date:   Mon Feb 3 16:00:50 2014 -0500

    slave: check object path validity before creating proxy from it
    
    This prevents a crash if the admin runs
    
    /usr/libexec/gdm-simple-slave --display-id something-invalid

 daemon/gdm-slave.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/daemon/gdm-slave.c b/daemon/gdm-slave.c
index 459eb20..a635488 100644
--- a/daemon/gdm-slave.c
+++ b/daemon/gdm-slave.c
@@ -676,6 +676,11 @@ gdm_slave_real_start (GdmSlave *slave)
 
         g_assert (slave->priv->display_proxy == NULL);
 
+        if (! g_variant_is_object_path (slave->priv->display_id)) {
+                g_warning ("Display ID isn't valid");
+                return FALSE;
+        }
+
         g_debug ("GdmSlave: Creating proxy for %s", slave->priv->display_id);
         error = NULL;
         slave->priv->display_proxy = GDM_DBUS_DISPLAY (gdm_dbus_display_proxy_new_sync 
(slave->priv->connection,