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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/184172">184172</a></dd>
<dt>Author</dt> <dd>carlosgc@webkit.org</dd>
<dt>Date</dt> <dd>2015-05-12 01:29:37 -0700 (Tue, 12 May 2015)</dd>
</dl>

<h3>Log Message</h3>
<pre>Merge <a href="http://trac.webkit.org/projects/webkit/changeset/183788">r183788</a> - RenderWidget::setWidgetGeometry() can end up destroying *this*.
https://bugs.webkit.org/show_bug.cgi?id=144601

Reviewed by Andreas Kling.

This is a speculative fix to ensure we don't crash on an invalid *this* renderer
while flattening the current iframe.
Calling RenderWidget::setWidgetGeometry() can result in destroying the current renderer.
While it is not a issue in case of normal layout flow as widget positions are updated at post layout,
frame flattening initiates this action in the middle of layout.
This patch re-introduces refcount model for RenderWidgets so that the renderer is protected during layout
when frame flattening is in use.

* rendering/RenderFrameBase.cpp:
(WebCore::RenderFrameBase::layoutWithFlattening): Let's be paranoid about child view.
* rendering/RenderObject.cpp:
(WebCore::RenderObject::destroy):
* rendering/FrameView.cpp:
(WebCore::FrameView::layout):
* rendering/RenderView.h:
* rendering/RenderWidget.cpp:
(WebCore::RenderWidget::~RenderWidget):
* rendering/RenderWidget.h:
(WebCore::RenderWidget::ref):
(WebCore::RenderWidget::deref):</pre>

<h3>Modified Paths</h3>
<ul>
<li><a href="#releasesWebKitGTKwebkit28SourceWebCoreChangeLog">releases/WebKitGTK/webkit-2.8/Source/WebCore/ChangeLog</a></li>
<li><a href="#releasesWebKitGTKwebkit28SourceWebCorepageFrameViewcpp">releases/WebKitGTK/webkit-2.8/Source/WebCore/page/FrameView.cpp</a></li>
<li><a href="#releasesWebKitGTKwebkit28SourceWebCorerenderingRenderFrameBasecpp">releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderFrameBase.cpp</a></li>
<li><a href="#releasesWebKitGTKwebkit28SourceWebCorerenderingRenderObjectcpp">releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderObject.cpp</a></li>
<li><a href="#releasesWebKitGTKwebkit28SourceWebCorerenderingRenderViewh">releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderView.h</a></li>
<li><a href="#releasesWebKitGTKwebkit28SourceWebCorerenderingRenderWidgetcpp">releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderWidget.cpp</a></li>
<li><a href="#releasesWebKitGTKwebkit28SourceWebCorerenderingRenderWidgeth">releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderWidget.h</a></li>
</ul>

</div>
<div id="patch">
<h3>Diff</h3>
<a id="releasesWebKitGTKwebkit28SourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.8/Source/WebCore/ChangeLog (184171 => 184172)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.8/Source/WebCore/ChangeLog        2015-05-12 08:15:53 UTC (rev 184171)
+++ releases/WebKitGTK/webkit-2.8/Source/WebCore/ChangeLog        2015-05-12 08:29:37 UTC (rev 184172)
</span><span class="lines">@@ -1,3 +1,31 @@
</span><ins>+2015-05-04  Zalan Bujtas  &lt;zalan@apple.com&gt;
+
+        RenderWidget::setWidgetGeometry() can end up destroying *this*.
+        https://bugs.webkit.org/show_bug.cgi?id=144601
+
+        Reviewed by Andreas Kling.
+
+        This is a speculative fix to ensure we don't crash on an invalid *this* renderer
+        while flattening the current iframe.
+        Calling RenderWidget::setWidgetGeometry() can result in destroying the current renderer.
+        While it is not a issue in case of normal layout flow as widget positions are updated at post layout,
+        frame flattening initiates this action in the middle of layout.
+        This patch re-introduces refcount model for RenderWidgets so that the renderer is protected during layout
+        when frame flattening is in use.
+
+        * rendering/RenderFrameBase.cpp:
+        (WebCore::RenderFrameBase::layoutWithFlattening): Let's be paranoid about child view.
+        * rendering/RenderObject.cpp:
+        (WebCore::RenderObject::destroy):
+        * rendering/FrameView.cpp:
+        (WebCore::FrameView::layout):
+        * rendering/RenderView.h:
+        * rendering/RenderWidget.cpp:
+        (WebCore::RenderWidget::~RenderWidget):
+        * rendering/RenderWidget.h:
+        (WebCore::RenderWidget::ref):
+        (WebCore::RenderWidget::deref):
+
</ins><span class="cx"> 2015-05-04  Chris Dumez  &lt;cdumez@apple.com&gt;
</span><span class="cx"> 
</span><span class="cx">         Crash at com.apple.WebKit.WebContent at com.apple.WebCore: WebCore::createWindow + 185
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit28SourceWebCorepageFrameViewcpp"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.8/Source/WebCore/page/FrameView.cpp (184171 => 184172)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.8/Source/WebCore/page/FrameView.cpp        2015-05-12 08:15:53 UTC (rev 184171)
+++ releases/WebKitGTK/webkit-2.8/Source/WebCore/page/FrameView.cpp        2015-05-12 08:29:37 UTC (rev 184172)
</span><span class="lines">@@ -1356,6 +1356,8 @@
</span><span class="cx">     if (m_needsFullRepaint)
</span><span class="cx">         root-&gt;view().repaintRootContents();
</span><span class="cx"> 
</span><ins>+    root-&gt;view().releaseProtectedRenderWidgets();
+
</ins><span class="cx">     ASSERT(!root-&gt;needsLayout());
</span><span class="cx"> 
</span><span class="cx">     layer-&gt;updateLayerPositionsAfterLayout(renderView()-&gt;layer(), updateLayerPositionFlags(layer, subtree, m_needsFullRepaint));
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit28SourceWebCorerenderingRenderFrameBasecpp"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderFrameBase.cpp (184171 => 184172)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderFrameBase.cpp        2015-05-12 08:15:53 UTC (rev 184171)
+++ releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderFrameBase.cpp        2015-05-12 08:29:37 UTC (rev 184172)
</span><span class="lines">@@ -54,13 +54,13 @@
</span><span class="cx"> 
</span><span class="cx"> void RenderFrameBase::layoutWithFlattening(bool hasFixedWidth, bool hasFixedHeight)
</span><span class="cx"> {
</span><del>-    FrameView* childFrameView = childView();
-    RenderView* childRoot = childFrameView ? childFrameView-&gt;frame().contentRenderer() : 0;
</del><ins>+    view().protectRenderWidgetUntilLayoutIsDone(*this);
+    RenderView* childRoot = childView() ? childView()-&gt;frame().contentRenderer() : 0;
</ins><span class="cx"> 
</span><span class="cx">     if (!childRoot || !shouldExpandFrame(width(), height(), hasFixedWidth, hasFixedHeight)) {
</span><span class="cx">         updateWidgetPosition();
</span><del>-        if (childFrameView)
-            childFrameView-&gt;layout();
</del><ins>+        if (childView())
+            childView()-&gt;layout();
</ins><span class="cx">         clearNeedsLayout();
</span><span class="cx">         return;
</span><span class="cx">     }
</span><span class="lines">@@ -83,18 +83,20 @@
</span><span class="cx">         setWidth(std::max(width(), childRoot-&gt;minPreferredLogicalWidth() + hBorder));
</span><span class="cx">         // update again to pass the new width to the child frame
</span><span class="cx">         updateWidgetPosition();
</span><del>-        childFrameView-&gt;layout();
</del><ins>+        if (childView())
+            childView()-&gt;layout();
</ins><span class="cx">     }
</span><span class="cx"> 
</span><del>-    // expand the frame by setting frame height = content height
-    if (isScrollable || !hasFixedHeight || childRoot-&gt;isFrameSet())
-        setHeight(std::max&lt;LayoutUnit&gt;(height(), childFrameView-&gt;contentsHeight() + vBorder));
-    if (isScrollable || !hasFixedWidth || childRoot-&gt;isFrameSet())
-        setWidth(std::max&lt;LayoutUnit&gt;(width(), childFrameView-&gt;contentsWidth() + hBorder));
-
</del><ins>+    if (childView()) {
+        // expand the frame by setting frame height = content height
+        if (isScrollable || !hasFixedHeight || childRoot-&gt;isFrameSet())
+            setHeight(std::max&lt;LayoutUnit&gt;(height(), childView()-&gt;contentsHeight() + vBorder));
+        if (isScrollable || !hasFixedWidth || childRoot-&gt;isFrameSet())
+            setWidth(std::max&lt;LayoutUnit&gt;(width(), childView()-&gt;contentsWidth() + hBorder));
+    }
</ins><span class="cx">     updateWidgetPosition();
</span><span class="cx"> 
</span><del>-    ASSERT(!childFrameView-&gt;layoutPending());
</del><ins>+    ASSERT(!childView()-&gt;layoutPending());
</ins><span class="cx">     ASSERT(!childRoot-&gt;needsLayout());
</span><span class="cx">     ASSERT(!childRoot-&gt;firstChild() || !childRoot-&gt;firstChild()-&gt;firstChildSlow() || !childRoot-&gt;firstChild()-&gt;firstChildSlow()-&gt;needsLayout());
</span><span class="cx"> 
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit28SourceWebCorerenderingRenderObjectcpp"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderObject.cpp (184171 => 184172)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderObject.cpp        2015-05-12 08:15:53 UTC (rev 184171)
+++ releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderObject.cpp        2015-05-12 08:29:37 UTC (rev 184172)
</span><span class="lines">@@ -60,6 +60,7 @@
</span><span class="cx"> #include &quot;RenderScrollbarPart.h&quot;
</span><span class="cx"> #include &quot;RenderTheme.h&quot;
</span><span class="cx"> #include &quot;RenderView.h&quot;
</span><ins>+#include &quot;RenderWidget.h&quot;
</ins><span class="cx"> #include &quot;SVGRenderSupport.h&quot;
</span><span class="cx"> #include &quot;Settings.h&quot;
</span><span class="cx"> #include &quot;StyleResolver.h&quot;
</span><span class="lines">@@ -2022,6 +2023,10 @@
</span><span class="cx"> #endif
</span><span class="cx"> 
</span><span class="cx">     willBeDestroyed();
</span><ins>+    if (is&lt;RenderWidget&gt;(*this)) {
+        downcast&lt;RenderWidget&gt;(*this).deref();
+        return;
+    }
</ins><span class="cx">     delete this;
</span><span class="cx"> }
</span><span class="cx"> 
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit28SourceWebCorerenderingRenderViewh"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderView.h (184171 => 184172)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderView.h        2015-05-12 08:15:53 UTC (rev 184171)
+++ releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderView.h        2015-05-12 08:29:37 UTC (rev 184172)
</span><span class="lines">@@ -26,6 +26,7 @@
</span><span class="cx"> #include &quot;LayoutState.h&quot;
</span><span class="cx"> #include &quot;Region.h&quot;
</span><span class="cx"> #include &quot;RenderBlockFlow.h&quot;
</span><ins>+#include &quot;RenderWidget.h&quot;
</ins><span class="cx"> #include &quot;SelectionSubtreeRoot.h&quot;
</span><span class="cx"> #include &lt;memory&gt;
</span><span class="cx"> #include &lt;wtf/HashSet.h&gt;
</span><span class="lines">@@ -245,6 +246,9 @@
</span><span class="cx">     void scheduleLazyRepaint(RenderBox&amp;);
</span><span class="cx">     void unscheduleLazyRepaint(RenderBox&amp;);
</span><span class="cx"> 
</span><ins>+    void protectRenderWidgetUntilLayoutIsDone(RenderWidget&amp; widget) { m_protectedRenderWidgets.append(&amp;widget); }
+    void releaseProtectedRenderWidgets() { m_protectedRenderWidgets.clear(); }
+
</ins><span class="cx"> protected:
</span><span class="cx">     virtual void mapLocalToContainer(const RenderLayerModelObject* repaintContainer, TransformState&amp;, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = 0) const override;
</span><span class="cx">     virtual const RenderObject* pushMappingToContainer(const RenderLayerModelObject* ancestorToStopAt, RenderGeometryMap&amp;) const override;
</span><span class="lines">@@ -363,6 +367,7 @@
</span><span class="cx">     bool m_hasFlippedBlockDescendants;
</span><span class="cx"> 
</span><span class="cx">     HashSet&lt;RenderElement*&gt; m_renderersWithPausedImageAnimation;
</span><ins>+    Vector&lt;RefPtr&lt;RenderWidget&gt;&gt; m_protectedRenderWidgets;
</ins><span class="cx"> 
</span><span class="cx"> #if ENABLE(SERVICE_CONTROLS)
</span><span class="cx">     SelectionRectGatherer m_selectionRectGatherer;
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit28SourceWebCorerenderingRenderWidgetcpp"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderWidget.cpp (184171 => 184172)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderWidget.cpp        2015-05-12 08:15:53 UTC (rev 184171)
+++ releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderWidget.cpp        2015-05-12 08:29:37 UTC (rev 184172)
</span><span class="lines">@@ -106,6 +106,7 @@
</span><span class="cx"> 
</span><span class="cx"> RenderWidget::~RenderWidget()
</span><span class="cx"> {
</span><ins>+    ASSERT(!m_refCount);
</ins><span class="cx"> }
</span><span class="cx"> 
</span><span class="cx"> // Widgets are always placed on integer boundaries, so rounding the size is actually
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit28SourceWebCorerenderingRenderWidgeth"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderWidget.h (184171 => 184172)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderWidget.h        2015-05-12 08:15:53 UTC (rev 184171)
+++ releases/WebKitGTK/webkit-2.8/Source/WebCore/rendering/RenderWidget.h        2015-05-12 08:29:37 UTC (rev 184172)
</span><span class="lines">@@ -74,6 +74,9 @@
</span><span class="cx"> 
</span><span class="cx">     WeakPtr&lt;RenderWidget&gt; createWeakPtr() { return m_weakPtrFactory.createWeakPtr(); }
</span><span class="cx"> 
</span><ins>+    void ref() { ++m_refCount; }
+    void deref();
+
</ins><span class="cx"> protected:
</span><span class="cx">     RenderWidget(HTMLFrameOwnerElement&amp;, Ref&lt;RenderStyle&gt;&amp;&amp;);
</span><span class="cx"> 
</span><span class="lines">@@ -102,8 +105,16 @@
</span><span class="cx">     WeakPtrFactory&lt;RenderWidget&gt; m_weakPtrFactory;
</span><span class="cx">     RefPtr&lt;Widget&gt; m_widget;
</span><span class="cx">     IntRect m_clipRect; // The rectangle needs to remain correct after scrolling, so it is stored in content view coordinates, and not clipped to window.
</span><ins>+    unsigned m_refCount { 1 };
</ins><span class="cx"> };
</span><span class="cx"> 
</span><ins>+inline void RenderWidget::deref()
+{
+    ASSERT(m_refCount);
+    if (!--m_refCount)
+        delete this;
+}
+
</ins><span class="cx"> } // namespace WebCore
</span><span class="cx"> 
</span><span class="cx"> SPECIALIZE_TYPE_TRAITS_RENDER_OBJECT(RenderWidget, isWidget())
</span></span></pre>
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