Make sure binding security checks don't pass if the frame is remote.

third_party/WebKit/Source/bindings/core/v8/BindingSecurity.cpp

 /*
  * Copyright (C) 2009 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 32 matching lines @@
 
 static bool isOriginAccessibleFromDOMWindow(const SecurityOrigin* targetOrigin, const LocalDOMWindow* accessingWindow)
 {
     return accessingWindow && accessingWindow->document()->getSecurityOrigin()->canAccessCheckSuborigins(targetOrigin);
 }
 
 static bool canAccessFrame(v8::Isolate* isolate, const LocalDOMWindow* accessingWindow, const SecurityOrigin* targetFrameOrigin, const DOMWindow* targetWindow, ExceptionState& exceptionState)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!(targetWindow && targetWindow->frame()) || targetWindow == targetWindow->frame()->domWindow());
 
-    if (isOriginAccessibleFromDOMWindow(targetFrameOrigin, accessingWindow))
+    // It's important to check that targetWindow is a LocalDOMWindow: it's
+    // possible for a remote frame and local frame to have the same security
+    // origin, depending on the model being used to allocate Frames between
+    // processes. See https://crbug.com/601629

[Charlie Reis, 2016/04/13 16:45:56]

nit: End with period, here and below (as you did in DOMWindow).

[dcheng, 2016/04/13 17:13:01]

Done.

+    if (targetWindow->isLocalDOMWindow() && isOriginAccessibleFromDOMWindow(targetFrameOrigin, accessingWindow))
         return true;
 
     if (targetWindow)
         exceptionState.throwSecurityError(targetWindow->sanitizedCrossDomainAccessErrorMessage(accessingWindow), targetWindow->crossDomainAccessErrorMessage(accessingWindow));
     return false;
 }
 
 static bool canAccessFrame(v8::Isolate* isolate, const LocalDOMWindow* accessingWindow, SecurityOrigin* targetFrameOrigin, const DOMWindow* targetWindow, SecurityReportingOption reportingOption = ReportSecurityError)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!(targetWindow && targetWindow->frame()) || targetWindow == targetWindow->frame()->domWindow());
 
-    if (isOriginAccessibleFromDOMWindow(targetFrameOrigin, accessingWindow))
+    // It's important to check that targetWindow is a LocalDOMWindow: it's
+    // possible for a remote frame and local frame to have the same security
+    // origin, depending on the model being used to allocate Frames between
+    // processes. See https://crbug.com/601629
+    if (targetWindow->isLocalDOMWindow() && isOriginAccessibleFromDOMWindow(targetFrameOrigin, accessingWindow))
         return true;
 
     if (reportingOption == ReportSecurityError && targetWindow)
         accessingWindow->printErrorMessage(targetWindow->crossDomainAccessErrorMessage(accessingWindow));
     return false;
 }
 
 bool BindingSecurity::shouldAllowAccessTo(v8::Isolate* isolate, const LocalDOMWindow* accessingWindow, const DOMWindow* target, ExceptionState& exceptionState)
 {
     ASSERT(target);
@@ skipping 70 matching lines @@
 }
 
 bool BindingSecurity::shouldAllowAccessToFrame(v8::Isolate* isolate, const LocalDOMWindow* accessingWindow, const Frame* target, SecurityReportingOption reportingOption)
 {
     if (!target || !target->securityContext())
         return false;
     return canAccessFrame(isolate, accessingWindow, target->securityContext()->getSecurityOrigin(), target->domWindow(), reportingOption);
 }
 
 } // namespace blink