Bug#638871: g_dbus_connection_register_object does not set error on some conditions

[Marcin Owsiany]

X-Debbugs-cc: libpanel-applet at packages.debian.org
Package: libglib2.0-0
Version: 2.28.6-1

The documentation for this function claims that the return value is 0
when "error" is set. However I have found a case where this is not true,
leading to a crash in libpanel-applet.

The code (in gnome-panel/libpanel-applet/panel-applet.c
panel_applet_register_object()) looks like this:

|        applet->priv->object_id =
|                g_dbus_connection_register_object (applet->priv->connection,
|                                                   applet->priv->object_path,
|                                                   introspection_data->interfaces[0],
|                                                   &interface_vtable,
|                                                   applet, NULL,
|                                                   &error);
|        if (!applet->priv->object_id) {
|                g_printerr ("Failed to register object %s: %s\n", applet->priv->object_path, error->message);
|                g_error_free (error);
|        }

And when an invalid object path is specified in the
applet->priv->object_path property, it leads to:

1) the following warning being issued:

(command_runner:1931): GLib-GIO-CRITICAL **:
g_dbus_connection_register_object: assertion `object_path != NULL &&
g_variant_is_object_path (object_path)' failed

and then:

2) Program received signal SIGSEGV, Segmentation fault.
0xb671726c in panel_applet_register_object (object=0x8536020)
    at panel-applet.c:2457

At panel-applet.c:2457 error->message is being dereferenced. After
inspecting with gdb, I can see that:

- "error" is NULL
- applet->priv->object_id is 0
- applet->priv->object_path is an invalid (as far as
  g_variant_is_object_path is concerned) string:
  "/org/gnome/panel/applet/Id=CommandRunnetApplet/0"


-- 
Marcin Owsiany <porridge at debian.org>             http://marcin.owsiany.pl/
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