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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/243820">243820</a></dd>
<dt>Author</dt> <dd>rniwa@webkit.org</dd>
<dt>Date</dt> <dd>2019-04-03 13:04:37 -0700 (Wed, 03 Apr 2019)</dd>
</dl>

<h3>Log Message</h3>
<pre>Crash in HTMLCanvasElement::createContext2d after the element got adopted to a new document
https://bugs.webkit.org/show_bug.cgi?id=196527

Reviewed by Antti Koivisto.

We need to update CanvasBase::m_scriptExecutionContext when HTMLCanvasElement moves from
one document to another. Fixed the bug by making CanvasBase::scriptExecutionContext make
a virtual function call instead of directly storing a raw pointer. In HTMLCanvasElement,
we use Node::scriptExecutionContext(). Use ContextDestructionObserver in CustomPaintCanvas
and OffscreenCanvas instead of a raw pointer.

Unfortunately, no new tests since there is no reproducible test case.

* html/CanvasBase.cpp:
(WebCore::CanvasBase::CanvasBase):
* html/CanvasBase.h:
(WebCore::CanvasBase::scriptExecutionContext const):
* html/CustomPaintCanvas.cpp:
(WebCore::CustomPaintCanvas::CustomPaintCanvas):
* html/CustomPaintCanvas.h:
* html/HTMLCanvasElement.cpp:
(WebCore::HTMLCanvasElement::HTMLCanvasElement):
* html/HTMLCanvasElement.h:
* html/OffscreenCanvas.cpp:
(WebCore::OffscreenCanvas::OffscreenCanvas):
* html/OffscreenCanvas.h:</pre>

<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceWebCoreChangeLog">trunk/Source/WebCore/ChangeLog</a></li>
<li><a href="#trunkSourceWebCorehtmlCanvasBasecpp">trunk/Source/WebCore/html/CanvasBase.cpp</a></li>
<li><a href="#trunkSourceWebCorehtmlCanvasBaseh">trunk/Source/WebCore/html/CanvasBase.h</a></li>
<li><a href="#trunkSourceWebCorehtmlCustomPaintCanvascpp">trunk/Source/WebCore/html/CustomPaintCanvas.cpp</a></li>
<li><a href="#trunkSourceWebCorehtmlCustomPaintCanvash">trunk/Source/WebCore/html/CustomPaintCanvas.h</a></li>
<li><a href="#trunkSourceWebCorehtmlHTMLCanvasElementcpp">trunk/Source/WebCore/html/HTMLCanvasElement.cpp</a></li>
<li><a href="#trunkSourceWebCorehtmlHTMLCanvasElementh">trunk/Source/WebCore/html/HTMLCanvasElement.h</a></li>
<li><a href="#trunkSourceWebCorehtmlOffscreenCanvascpp">trunk/Source/WebCore/html/OffscreenCanvas.cpp</a></li>
<li><a href="#trunkSourceWebCorehtmlOffscreenCanvash">trunk/Source/WebCore/html/OffscreenCanvas.h</a></li>
</ul>

</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/ChangeLog (243819 => 243820)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/ChangeLog   2019-04-03 19:47:58 UTC (rev 243819)
+++ trunk/Source/WebCore/ChangeLog      2019-04-03 20:04:37 UTC (rev 243820)
</span><span class="lines">@@ -1,3 +1,32 @@
</span><ins>+2019-04-02  Ryosuke Niwa  <rniwa@webkit.org>
+
+        Crash in HTMLCanvasElement::createContext2d after the element got adopted to a new document
+        https://bugs.webkit.org/show_bug.cgi?id=196527
+
+        Reviewed by Antti Koivisto.
+
+        We need to update CanvasBase::m_scriptExecutionContext when HTMLCanvasElement moves from
+        one document to another. Fixed the bug by making CanvasBase::scriptExecutionContext make
+        a virtual function call instead of directly storing a raw pointer. In HTMLCanvasElement,
+        we use Node::scriptExecutionContext(). Use ContextDestructionObserver in CustomPaintCanvas
+        and OffscreenCanvas instead of a raw pointer.
+
+        Unfortunately, no new tests since there is no reproducible test case.
+
+        * html/CanvasBase.cpp:
+        (WebCore::CanvasBase::CanvasBase):
+        * html/CanvasBase.h:
+        (WebCore::CanvasBase::scriptExecutionContext const):
+        * html/CustomPaintCanvas.cpp:
+        (WebCore::CustomPaintCanvas::CustomPaintCanvas):
+        * html/CustomPaintCanvas.h:
+        * html/HTMLCanvasElement.cpp:
+        (WebCore::HTMLCanvasElement::HTMLCanvasElement):
+        * html/HTMLCanvasElement.h:
+        * html/OffscreenCanvas.cpp:
+        (WebCore::OffscreenCanvas::OffscreenCanvas):
+        * html/OffscreenCanvas.h:
+
</ins><span class="cx"> 2019-04-03  Myles C. Maxfield  <mmaxfield@apple.com>
</span><span class="cx"> 
</span><span class="cx">         Remove support for -apple-trailing-word
</span></span></pre></div>
<a id="trunkSourceWebCorehtmlCanvasBasecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/html/CanvasBase.cpp (243819 => 243820)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/html/CanvasBase.cpp 2019-04-03 19:47:58 UTC (rev 243819)
+++ trunk/Source/WebCore/html/CanvasBase.cpp    2019-04-03 20:04:37 UTC (rev 243820)
</span><span class="lines">@@ -35,8 +35,7 @@
</span><span class="cx"> 
</span><span class="cx"> namespace WebCore {
</span><span class="cx"> 
</span><del>-CanvasBase::CanvasBase(ScriptExecutionContext* scriptExecutionContext)
-    : m_scriptExecutionContext(scriptExecutionContext)
</del><ins>+CanvasBase::CanvasBase()
</ins><span class="cx"> {
</span><span class="cx"> }
</span><span class="cx"> 
</span></span></pre></div>
<a id="trunkSourceWebCorehtmlCanvasBaseh"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/html/CanvasBase.h (243819 => 243820)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/html/CanvasBase.h   2019-04-03 19:47:58 UTC (rev 243819)
+++ trunk/Source/WebCore/html/CanvasBase.h      2019-04-03 20:04:37 UTC (rev 243820)
</span><span class="lines">@@ -74,7 +74,7 @@
</span><span class="cx">     bool originClean() const { return m_originClean; }
</span><span class="cx"> 
</span><span class="cx">     virtual SecurityOrigin* securityOrigin() const { return nullptr; }
</span><del>-    ScriptExecutionContext* scriptExecutionContext() const { return m_scriptExecutionContext; }
</del><ins>+    ScriptExecutionContext* scriptExecutionContext() const { return canvasBaseScriptExecutionContext();  }
</ins><span class="cx"> 
</span><span class="cx">     CanvasRenderingContext* renderingContext() const;
</span><span class="cx"> 
</span><span class="lines">@@ -98,8 +98,10 @@
</span><span class="cx">     bool callTracingActive() const;
</span><span class="cx"> 
</span><span class="cx"> protected:
</span><del>-    CanvasBase(ScriptExecutionContext*);
</del><ins>+    CanvasBase();
</ins><span class="cx"> 
</span><ins>+    virtual ScriptExecutionContext* canvasBaseScriptExecutionContext() const = 0;
+
</ins><span class="cx">     std::unique_ptr<CanvasRenderingContext> m_context;
</span><span class="cx"> 
</span><span class="cx"> private:
</span><span class="lines">@@ -107,7 +109,6 @@
</span><span class="cx"> #ifndef NDEBUG
</span><span class="cx">     bool m_didNotifyObserversCanvasDestroyed { false };
</span><span class="cx"> #endif
</span><del>-    ScriptExecutionContext* m_scriptExecutionContext;
</del><span class="cx">     HashSet<CanvasObserver*> m_observers;
</span><span class="cx"> };
</span><span class="cx"> 
</span></span></pre></div>
<a id="trunkSourceWebCorehtmlCustomPaintCanvascpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/html/CustomPaintCanvas.cpp (243819 => 243820)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/html/CustomPaintCanvas.cpp  2019-04-03 19:47:58 UTC (rev 243819)
+++ trunk/Source/WebCore/html/CustomPaintCanvas.cpp     2019-04-03 20:04:37 UTC (rev 243820)
</span><span class="lines">@@ -39,7 +39,7 @@
</span><span class="cx"> }
</span><span class="cx"> 
</span><span class="cx"> CustomPaintCanvas::CustomPaintCanvas(ScriptExecutionContext& context, unsigned width, unsigned height)
</span><del>-    : CanvasBase(&context)
</del><ins>+    : ContextDestructionObserver(&context)
</ins><span class="cx">     , m_size(width, height)
</span><span class="cx"> {
</span><span class="cx"> }
</span></span></pre></div>
<a id="trunkSourceWebCorehtmlCustomPaintCanvash"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/html/CustomPaintCanvas.h (243819 => 243820)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/html/CustomPaintCanvas.h    2019-04-03 19:47:58 UTC (rev 243819)
+++ trunk/Source/WebCore/html/CustomPaintCanvas.h       2019-04-03 20:04:37 UTC (rev 243820)
</span><span class="lines">@@ -44,7 +44,7 @@
</span><span class="cx"> class ImageBitmap;
</span><span class="cx"> class PaintRenderingContext2D;
</span><span class="cx"> 
</span><del>-class CustomPaintCanvas final : public RefCounted<CustomPaintCanvas>, public CanvasBase {
</del><ins>+class CustomPaintCanvas final : public RefCounted<CustomPaintCanvas>, public CanvasBase, private ContextDestructionObserver {
</ins><span class="cx">     WTF_MAKE_FAST_ALLOCATED;
</span><span class="cx"> public:
</span><span class="cx"> 
</span><span class="lines">@@ -80,6 +80,7 @@
</span><span class="cx"> 
</span><span class="cx">     void refCanvasBase() final { ref(); }
</span><span class="cx">     void derefCanvasBase() final { deref(); }
</span><ins>+    ScriptExecutionContext* canvasBaseScriptExecutionContext() const final { return ContextDestructionObserver::scriptExecutionContext(); }
</ins><span class="cx"> 
</span><span class="cx">     mutable GraphicsContext* m_destinationGraphicsContext = nullptr;
</span><span class="cx">     mutable IntSize m_size;
</span></span></pre></div>
<a id="trunkSourceWebCorehtmlHTMLCanvasElementcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/html/HTMLCanvasElement.cpp (243819 => 243820)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/html/HTMLCanvasElement.cpp  2019-04-03 19:47:58 UTC (rev 243819)
+++ trunk/Source/WebCore/html/HTMLCanvasElement.cpp     2019-04-03 20:04:37 UTC (rev 243820)
</span><span class="lines">@@ -116,7 +116,6 @@
</span><span class="cx"> 
</span><span class="cx"> HTMLCanvasElement::HTMLCanvasElement(const QualifiedName& tagName, Document& document)
</span><span class="cx">     : HTMLElement(tagName, document)
</span><del>-    , CanvasBase(&document)
</del><span class="cx">     , m_size(defaultWidth, defaultHeight)
</span><span class="cx"> {
</span><span class="cx">     ASSERT(hasTagName(canvasTag));
</span></span></pre></div>
<a id="trunkSourceWebCorehtmlHTMLCanvasElementh"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/html/HTMLCanvasElement.h (243819 => 243820)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/html/HTMLCanvasElement.h    2019-04-03 19:47:58 UTC (rev 243819)
+++ trunk/Source/WebCore/html/HTMLCanvasElement.h       2019-04-03 20:04:37 UTC (rev 243820)
</span><span class="lines">@@ -179,6 +179,8 @@
</span><span class="cx">     void refCanvasBase() final { HTMLElement::ref(); }
</span><span class="cx">     void derefCanvasBase() final { HTMLElement::deref(); }
</span><span class="cx"> 
</span><ins>+    ScriptExecutionContext* canvasBaseScriptExecutionContext() const final { return HTMLElement::scriptExecutionContext(); }
+
</ins><span class="cx">     FloatRect m_dirtyRect;
</span><span class="cx">     mutable IntSize m_size;
</span><span class="cx"> 
</span></span></pre></div>
<a id="trunkSourceWebCorehtmlOffscreenCanvascpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/html/OffscreenCanvas.cpp (243819 => 243820)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/html/OffscreenCanvas.cpp    2019-04-03 19:47:58 UTC (rev 243819)
+++ trunk/Source/WebCore/html/OffscreenCanvas.cpp       2019-04-03 20:04:37 UTC (rev 243820)
</span><span class="lines">@@ -38,7 +38,7 @@
</span><span class="cx"> }
</span><span class="cx"> 
</span><span class="cx"> OffscreenCanvas::OffscreenCanvas(ScriptExecutionContext& context, unsigned width, unsigned height)
</span><del>-    : CanvasBase(&context)
</del><ins>+    : ContextDestructionObserver(&context)
</ins><span class="cx">     , m_size(width, height)
</span><span class="cx"> {
</span><span class="cx"> }
</span></span></pre></div>
<a id="trunkSourceWebCorehtmlOffscreenCanvash"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/html/OffscreenCanvas.h (243819 => 243820)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/html/OffscreenCanvas.h      2019-04-03 19:47:58 UTC (rev 243819)
+++ trunk/Source/WebCore/html/OffscreenCanvas.h 2019-04-03 20:04:37 UTC (rev 243820)
</span><span class="lines">@@ -45,7 +45,7 @@
</span><span class="cx"> using OffscreenRenderingContext = RefPtr<WebGLRenderingContext>;
</span><span class="cx"> #endif
</span><span class="cx"> 
</span><del>-class OffscreenCanvas final : public RefCounted<OffscreenCanvas>, public CanvasBase, public EventTargetWithInlineData {
</del><ins>+class OffscreenCanvas final : public RefCounted<OffscreenCanvas>, public CanvasBase, public EventTargetWithInlineData, private ContextDestructionObserver {
</ins><span class="cx">     WTF_MAKE_FAST_ALLOCATED;
</span><span class="cx"> public:
</span><span class="cx"> 
</span><span class="lines">@@ -94,7 +94,8 @@
</span><span class="cx"> 
</span><span class="cx">     bool isOffscreenCanvas() const final { return true; }
</span><span class="cx"> 
</span><del>-    ScriptExecutionContext* scriptExecutionContext() const final { return CanvasBase::scriptExecutionContext(); }
</del><ins>+    ScriptExecutionContext* scriptExecutionContext() const final { return ContextDestructionObserver::scriptExecutionContext(); }
+    ScriptExecutionContext* canvasBaseScriptExecutionContext() const final { return ContextDestructionObserver::scriptExecutionContext(); }
</ins><span class="cx"> 
</span><span class="cx">     EventTargetInterface eventTargetInterface() const final { return OffscreenCanvasEventTargetInterfaceType; }
</span><span class="cx">     void refEventTarget() final { ref(); }
</span></span></pre>
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