From de383809f668ae5670777f2219532c66bddec72a Mon Sep 17 00:00:00 2001
From: Olivier Fourdan <ofourdan@redhat.com>
Date: Mon, 29 Feb 2016 10:14:56 +0100
Subject: [PATCH] wayland: Check actual impl type in transient loop

If the parent of a transient is not a native Wayland window (e.g.
offscreen window), the transient loop check will crash.

Check for the actual type in the transient loop check and do not assume
the parent is necessarily Wayland native.

bugzilla: https://bugzilla.gnome.org/show_bug.cgi?id=761156

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
---
 gdk/wayland/gdkwindow-wayland.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/gdk/wayland/gdkwindow-wayland.c b/gdk/wayland/gdkwindow-wayland.c
index 34c6805ce8..9439c1abc6 100644
--- a/gdk/wayland/gdkwindow-wayland.c
+++ b/gdk/wayland/gdkwindow-wayland.c
@@ -946,8 +946,12 @@ gdk_wayland_window_update_dialogs (GdkWindow *window)
   for (l = orphan_dialogs; l; l = l->next)
     {
       GdkWindow *w = l->data;
-      GdkWindowImplWayland *impl = GDK_WINDOW_IMPL_WAYLAND (w->impl);
+      GdkWindowImplWayland *impl;
 
+      if (!GDK_IS_WINDOW_IMPL_WAYLAND(w->impl))
+        continue;
+
+      impl = GDK_WINDOW_IMPL_WAYLAND (w->impl);
       if (w == window)
 	continue;
       if (impl->hint != GDK_WINDOW_TYPE_HINT_DIALOG)
@@ -2215,8 +2219,12 @@ check_transient_for_loop (GdkWindow *window,
 {
   while (parent)
     {
-      GdkWindowImplWayland *impl = GDK_WINDOW_IMPL_WAYLAND (parent->impl);
+      GdkWindowImplWayland *impl;
 
+      if (!GDK_IS_WINDOW_IMPL_WAYLAND(parent->impl))
+        return FALSE;
+
+      impl = GDK_WINDOW_IMPL_WAYLAND (parent->impl);
       if (impl->transient_for == window)
         return TRUE;
       parent = impl->transient_for;