AX:Null pointer may be dereferenced in AXObjectCache.cpp

Source/core/accessibility/AXObjectCache.cpp

 /*
  * Copyright (C) 2008, 2009, 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 325 matching lines @@
 
     RefPtr<AXObject> newObj = 0;
     if (widget->isFrameView())
         newObj = AXScrollView::create(toScrollView(widget));
     else if (widget->isScrollbar())
         newObj = AXScrollbar::create(toScrollbar(widget));
 
     // Will crash later if we have two objects for the same widget.
     ASSERT(!get(widget));
 
+    // Catch the case if an (unsupported) widget type is used. Only FrameView and ScrollBar are supported now.
+    ASSERT(newObj);
+    if (!newObj)
+        return 0;
+
     getAXID(newObj.get());
 
     m_widgetObjectMapping.set(widget, newObj->axObjectID());
     m_objects.set(newObj->axObjectID(), newObj);
     newObj->init();
     attachWrapper(newObj.get());
     return newObj.get();
 }
 
 AXObject* AXObjectCache::getOrCreate(Node* node)
@@ skipping 663 matching lines @@
 }
 
 void AXObjectCache::handleScrolledToAnchor(const Node* anchorNode)
 {
     // The anchor node may not be accessible. Post the notification for the
     // first accessible object.
     postPlatformNotification(AXObject::firstAccessibleObjectFromNode(anchorNode), AXScrolledToAnchor);
 }
 
 } // namespace WebCore