From 743244a69cd37d5981fc5603af58d19cc07c0f72 Mon Sep 17 00:00:00 2001
From: Thomas Geymayer <tomgey@gmail.com>
Date: Sun, 10 Nov 2013 17:12:50 +0100
Subject: [PATCH] CanvasElement: ensure parent pointer can not become invalid.

---
 simgear/canvas/elements/CanvasElement.cxx | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/simgear/canvas/elements/CanvasElement.cxx b/simgear/canvas/elements/CanvasElement.cxx
index 49c7a47b..b6e83056 100644
--- a/simgear/canvas/elements/CanvasElement.cxx
+++ b/simgear/canvas/elements/CanvasElement.cxx
@@ -108,7 +108,19 @@ namespace canvas
   //----------------------------------------------------------------------------
   Element::~Element()
   {
+    if( !_transform.valid() )
+      return;
 
+    for(unsigned int i = 0; i < _transform->getNumChildren(); ++i)
+    {
+      OSGUserData* ud =
+        static_cast<OSGUserData*>(_transform->getChild(i)->getUserData());
+
+      if( ud )
+        // Ensure parent is cleared to prevent accessing released memory if an
+        // element somehow survives longer than his parent.
+        ud->element->_parent = 0;
+    }
   }
 
   //----------------------------------------------------------------------------