MetaPluginManager: don't try to deference a NULL pointer when processing events

This function might be called by components with invalid plugin manager
(as it might happen to MetaWindow when the compositor isn't initialized
properly), so we need to protect ourselves from crashes.

https://bugzilla.gnome.org/show_bug.cgi?id=789223

1 files changed, 11 insertions, 4 deletions

diff --git a/src/compositor/meta-plugin-manager.c b/src/compositor/meta-plugin-manager.c
index 834f678dd..9f6e67273 100644
--- a/src/compositor/meta-plugin-manager.c
+++ b/src/compositor/meta-plugin-manager.c
@@ -153,10 +153,17 @@ meta_plugin_manager_event_simple (MetaPluginManager *plugin_mgr,
                                   MetaWindowActor   *actor,
                                   MetaPluginEffect   event)
 {
-  MetaPlugin *plugin = plugin_mgr->plugin;
-  MetaPluginClass *klass = META_PLUGIN_GET_CLASS (plugin);
-  MetaDisplay *display = plugin_mgr->compositor->display;
-  gboolean retval = FALSE;
+  MetaPlugin *plugin;
+  MetaPluginClass *klass;
+  MetaDisplay *display;
+  gboolean retval;
+
+  g_return_val_if_fail (plugin_mgr, FALSE);
+
+  plugin = plugin_mgr->plugin;
+  klass = META_PLUGIN_GET_CLASS (plugin);
+  display = plugin_mgr->compositor->display;
+  retval = FALSE;
 
   if (display->display_opening)
     return FALSE;