From d0de667ec276eaca115a00b0c7b0010488459ae9 Mon Sep 17 00:00:00 2001
From: "Daniel P. Berrange" <berrange@redhat.com>
Date: Tue, 8 May 2012 14:39:44 +0100
Subject: [PATCH] Avoid race condition when disposing of app

When disposing of the VirtViewerApp, we free the hash table
containing the windows. This causes each window to be freed,
which in turn causes the visibility callback to be invoked.
This can then get NULL pointers from the self->priv->windows
usage.

Blank out priv->windows before unrefing the hashs and add
a check to ensure priv->windows is non-NULL.
---
 src/virt-viewer-app.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/virt-viewer-app.c b/src/virt-viewer-app.c
index 82149dc..b2f42ca 100644
--- a/src/virt-viewer-app.c
+++ b/src/virt-viewer-app.c
@@ -1254,9 +1254,13 @@ virt_viewer_app_dispose (GObject *object)
     VirtViewerAppPrivate *priv = self->priv;
 
     if (priv->windows) {
-        g_hash_table_unref(priv->windows);
+        GHashTable *tmp = priv->windows;
+        /* null-ify before unrefing, because we need
+         * to prevent callbacks using priv->windows
+         * while it is being disposed off. */
         priv->windows = NULL;
         priv->main_window = NULL;
+        g_hash_table_unref(tmp);
     }
 
     if (priv->container) {
@@ -1636,6 +1640,8 @@ window_update_menu_displays_cb(gpointer key G_GNUC_UNUSED,
 static void
 virt_viewer_app_update_menu_displays(VirtViewerApp *self)
 {
+    if (!self->priv->windows)
+        return;
     g_hash_table_foreach(self->priv->windows, window_update_menu_displays_cb, self);
 }