Protect the provisional loader from detaching during prepareForCommit

third_party/WebKit/Source/core/loader/FrameLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008 Alp Toker <alp@atoker.com>
  * Copyright (C) Research In Motion Limited 2009. All rights reserved.
  * Copyright (C) 2011 Kris Jordan <krisjordan@gmail.com>
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ skipping 150 matching lines @@
 FrameLoader::FrameLoader(LocalFrame* frame)
     : m_frame(frame)
     , m_progressTracker(ProgressTracker::create(frame))
     , m_loadType(FrameLoadTypeStandard)
     , m_inStopAllLoaders(false)
     , m_checkTimer(this, &FrameLoader::checkTimerFired)
     , m_didAccessInitialDocument(false)
     , m_didAccessInitialDocumentTimer(this, &FrameLoader::didAccessInitialDocumentTimerFired)
     , m_forcedSandboxFlags(SandboxNone)
     , m_dispatchingDidClearWindowObjectInMainWorld(false)
+    , m_protectProvisionalLoader(false)
 {
 }
 
 FrameLoader::~FrameLoader()
 {
     // Verify that this FrameLoader has been detached.
     ASSERT(!m_progressTracker);
 }
 
 DEFINE_TRACE(FrameLoader)
@@ skipping 496 matching lines @@
     client()->dispatchDidNavigateWithinPage(m_currentItem.get(), historyCommitType);
     client()->dispatchDidReceiveTitle(m_frame->document()->title());
     if (m_frame->document()->loadEventFinished())
         client()->didStopLoading();
 }
 
 void FrameLoader::detachDocumentLoader(RefPtrWillBeMember<DocumentLoader>& loader)
 {
     if (!loader)
         return;
+    if (loader == m_provisionalDocumentLoader && m_protectProvisionalLoader)
+        return;
 
     loader->detachFromFrame();
     loader = nullptr;
 }
 
 void FrameLoader::loadInSameDocument(const KURL& url, PassRefPtr<SerializedScriptValue> stateObject, FrameLoadType frameLoadType, HistoryLoadType historyLoadType, ClientRedirectPolicy clientRedirect)
 {
     // If we have a state object, we cannot also be a new navigation.
     ASSERT(!stateObject || frameLoadType == FrameLoadTypeBackForward);
 
@@ skipping 358 matching lines @@
         client()->dispatchWillClose();
         dispatchUnloadEvent();
     }
     m_frame->detachChildren();
     // The previous calls to dispatchUnloadEvent() and detachChildren() can
     // execute arbitrary script via things like unload events. If the executed
     // script intiates a new load or causes the current frame to be detached,
     // we need to abandon the current load.
     if (pdl != m_provisionalDocumentLoader)
         return false;
+    // detachFromFrame() will abort XHRs that haven't completed, which can
+    // trigger event listeners for 'abort'. These event listeners might call
+    // stop(), which will in turn detach the provisional document loader.
+    // At this point, the provisional document loader should not detach, because
+    // then the FrameLoader would not have any attached DocumentLoaders.
     if (m_documentLoader) {
         FrameNavigationDisabler navigationDisabler(*m_frame);
+        m_protectProvisionalLoader = false;

[dcheng, 2016/02/19 18:34:40]

Shouldn't this be true?

Also, maybe use TemporaryChange for this.

         detachDocumentLoader(m_documentLoader);
+        m_protectProvisionalLoader = false;
     }
-    // detachFromFrame() will abort XHRs that haven't completed, which can
-    // trigger event listeners for 'abort'. These event listeners might detach
-    // the frame.
+    // 'abort' listeners can also detach the frame.
     // TODO(dcheng): Investigate if this can be moved above the check that
     // m_provisionalDocumentLoader hasn't changed.
     if (!m_frame->client())
         return false;
     // No more events will be dispatched so detach the Document.
     // TODO(yoav): Should we also be nullifying domWindow's document (or domWindow) since the doc is now detached?
     if (m_frame->document())
         m_frame->document()->detach();
+    ASSERT(m_provisionalDocumentLoader);
     m_documentLoader = m_provisionalDocumentLoader.release();
 
     return true;
 }
 
 void FrameLoader::commitProvisionalLoad()
 {
     ASSERT(client()->hasWebView());
     RefPtrWillBeRawPtr<LocalFrame> protect(m_frame.get());
 
@@ skipping 471 matching lines @@
     // FIXME: We need a way to propagate insecure requests policy flags to
     // out-of-process frames. For now, we'll always use default behavior.
     if (!parentFrame->isLocalFrame())
         return nullptr;
 
     ASSERT(toLocalFrame(parentFrame)->document());
     return toLocalFrame(parentFrame)->document()->insecureNavigationsToUpgrade();
 }
 
 } // namespace blink