HTMLImageElement::cachedImage() may return null in ImageDocument construction

third_party/WebKit/Source/core/html/ImageDocument.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 209 matching lines @@
     body->setAttribute(styleAttr, "margin: 0px;");
 
     if (frame())
         frame()->loader().client()->dispatchWillInsertBody();
 
     m_imageElement = HTMLImageElement::create(*this);
     m_imageElement->setAttribute(styleAttr, "-webkit-user-select: none");
     m_imageElement->setLoadingImageDocument();
     m_imageElement->setSrc(url().getString());
     body->appendChild(m_imageElement.get());
-    if (loader())
+    if (loader() && m_imageElement->cachedImage())

[Nate Chapin, 2016/03/15 21:27:53]

Do we know why this can be null? It's not immediately obvious to me how that can
happen.

[yhirano, 2016/03/16 08:40:48]

ImageResource::fetch can return null. In ImageLoader[1] we are checking it after
creating an ImageResource which is the ImageResource returned from
m_imageElement->cachedImage().

I can create a crashing example locally with devtool's experimental "URL
blocking" functionality[2], though adding a layout test looks difficult.

1:
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...
2:
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

         m_imageElement->cachedImage()->responseReceived(loader()->response(), nullptr);
 
     if (shouldShrinkToFit()) {
         // Add event listeners
         RefPtrWillBeRawPtr<EventListener> listener = ImageEventListener::create(this);
         if (LocalDOMWindow* domWindow = this->domWindow())
             domWindow->addEventListener("resize", listener, false);
         if (m_shrinkToFitMode == Desktop)
             m_imageElement->addEventListener("click", listener.release(), false);
     }
@@ skipping 202 matching lines @@
 }
 
 bool ImageEventListener::operator==(const EventListener& listener) const
 {
     if (const ImageEventListener* imageEventListener = ImageEventListener::cast(&listener))
         return m_doc == imageEventListener->m_doc;
     return false;
 }
 
 } // namespace blink