<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head><meta http-equiv="content-type" content="text/html; charset=utf-8" />
<title>[184094] releases/WebKitGTK/webkit-2.8/Source/WebCore</title>
</head>
<body>
<style type="text/css"><!--
#msg dl.meta { border: 1px #006 solid; background: #369; padding: 6px; color: #fff; }
#msg dl.meta dt { float: left; width: 6em; font-weight: bold; }
#msg dt:after { content:':';}
#msg dl, #msg dt, #msg ul, #msg li, #header, #footer, #logmsg { font-family: verdana,arial,helvetica,sans-serif; font-size: 10pt; }
#msg dl a { font-weight: bold}
#msg dl a:link { color:#fc3; }
#msg dl a:active { color:#ff0; }
#msg dl a:visited { color:#cc6; }
h3 { font-family: verdana,arial,helvetica,sans-serif; font-size: 10pt; font-weight: bold; }
#msg pre { overflow: auto; background: #ffc; border: 1px #fa0 solid; padding: 6px; }
#logmsg { background: #ffc; border: 1px #fa0 solid; padding: 1em 1em 0 1em; }
#logmsg p, #logmsg pre, #logmsg blockquote { margin: 0 0 1em 0; }
#logmsg p, #logmsg li, #logmsg dt, #logmsg dd { line-height: 14pt; }
#logmsg h1, #logmsg h2, #logmsg h3, #logmsg h4, #logmsg h5, #logmsg h6 { margin: .5em 0; }
#logmsg h1:first-child, #logmsg h2:first-child, #logmsg h3:first-child, #logmsg h4:first-child, #logmsg h5:first-child, #logmsg h6:first-child { margin-top: 0; }
#logmsg ul, #logmsg ol { padding: 0; list-style-position: inside; margin: 0 0 0 1em; }
#logmsg ul { text-indent: -1em; padding-left: 1em; }#logmsg ol { text-indent: -1.5em; padding-left: 1.5em; }
#logmsg > ul, #logmsg > ol { margin: 0 0 1em 0; }
#logmsg pre { background: #eee; padding: 1em; }
#logmsg blockquote { border: 1px solid #fa0; border-left-width: 10px; padding: 1em 1em 0 1em; background: white;}
#logmsg dl { margin: 0; }
#logmsg dt { font-weight: bold; }
#logmsg dd { margin: 0; padding: 0 0 0.5em 0; }
#logmsg dd:before { content:'\00bb';}
#logmsg table { border-spacing: 0px; border-collapse: collapse; border-top: 4px solid #fa0; border-bottom: 1px solid #fa0; background: #fff; }
#logmsg table th { text-align: left; font-weight: normal; padding: 0.2em 0.5em; border-top: 1px dotted #fa0; }
#logmsg table td { text-align: right; border-top: 1px dotted #fa0; padding: 0.2em 0.5em; }
#logmsg table thead th { text-align: center; border-bottom: 1px solid #fa0; }
#logmsg table th.Corner { text-align: left; }
#logmsg hr { border: none 0; border-top: 2px dashed #fa0; height: 1px; }
#header, #footer { color: #fff; background: #636; border: 1px #300 solid; padding: 6px; }
#patch { width: 100%; }
#patch h4 {font-family: verdana,arial,helvetica,sans-serif;font-size:10pt;padding:8px;background:#369;color:#fff;margin:0;}
#patch .propset h4, #patch .binary h4 {margin:0;}
#patch pre {padding:0;line-height:1.2em;margin:0;}
#patch .diff {width:100%;background:#eee;padding: 0 0 10px 0;overflow:auto;}
#patch .propset .diff, #patch .binary .diff {padding:10px 0;}
#patch span {display:block;padding:0 10px;}
#patch .modfile, #patch .addfile, #patch .delfile, #patch .propset, #patch .binary, #patch .copfile {border:1px solid #ccc;margin:10px 0;}
#patch ins {background:#dfd;text-decoration:none;display:block;padding:0 10px;}
#patch del {background:#fdd;text-decoration:none;display:block;padding:0 10px;}
#patch .lines, .info {color:#888;background:#fff;}
--></style>
<div id="msg">
<dl class="meta">
<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/184094">184094</a></dd>
<dt>Author</dt> <dd>carlosgc@webkit.org</dd>
<dt>Date</dt> <dd>2015-05-11 06:41:28 -0700 (Mon, 11 May 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>Merge <a href="http://trac.webkit.org/projects/webkit/changeset/183178">r183178</a> - CrashTracer: WebProcess at com.apple.WebCore: WebCore::toScriptElementIfPossible + 4
https://bugs.webkit.org/show_bug.cgi?id=144050
rdar://problem/15534973
Reviewed by Chris Dumez.
We are seeing null Element pointer crashes with this stack:
47 com.apple.WebCore: WebCore::toScriptElementIfPossible + 4 <==
47 com.apple.WebCore: WebCore::ScriptRunner::timerFired + 452
47 com.apple.WebCore: WebCore::ThreadTimers::sharedTimerFiredInternal + 175
The most likely cause seems to be that this code
ASSERT(m_pendingAsyncScripts.contains(scriptElement));
m_scriptsToExecuteSoon.append(m_pendingAsyncScripts.take(scriptElement));
in ScriptRunner::notifyScriptReady fails to find scriptElement and we are left with a null entry in
m_scriptsToExecuteSoon. However I haven't managed to repro this or find the exact path how this
could happen. The related code is fragile with lot of state (in ScriptElement class)
and involves many opportunities for re-entry via scripts.
No repro, no test case.
* dom/ScriptRunner.cpp:
(WebCore::ScriptRunner::timerFired):
Paper this over by adding a null check. We could check m_pendingAsyncScripts.take() above
but this also covers possibility this is caused by something else.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#releasesWebKitGTKwebkit28SourceWebCoreChangeLog">releases/WebKitGTK/webkit-2.8/Source/WebCore/ChangeLog</a></li>
<li><a href="#releasesWebKitGTKwebkit28SourceWebCoredomScriptRunnercpp">releases/WebKitGTK/webkit-2.8/Source/WebCore/dom/ScriptRunner.cpp</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 (184093 => 184094)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.8/Source/WebCore/ChangeLog 2015-05-11 13:38:50 UTC (rev 184093)
+++ releases/WebKitGTK/webkit-2.8/Source/WebCore/ChangeLog 2015-05-11 13:41:28 UTC (rev 184094)
</span><span class="lines">@@ -1,3 +1,35 @@
</span><ins>+2015-04-22 Antti Koivisto <antti@apple.com>
+
+ CrashTracer: WebProcess at com.apple.WebCore: WebCore::toScriptElementIfPossible + 4
+ https://bugs.webkit.org/show_bug.cgi?id=144050
+ rdar://problem/15534973
+
+ Reviewed by Chris Dumez.
+
+ We are seeing null Element pointer crashes with this stack:
+
+ 47 com.apple.WebCore: WebCore::toScriptElementIfPossible + 4 <==
+ 47 com.apple.WebCore: WebCore::ScriptRunner::timerFired + 452
+ 47 com.apple.WebCore: WebCore::ThreadTimers::sharedTimerFiredInternal + 175
+
+ The most likely cause seems to be that this code
+
+ ASSERT(m_pendingAsyncScripts.contains(scriptElement));
+ m_scriptsToExecuteSoon.append(m_pendingAsyncScripts.take(scriptElement));
+
+ in ScriptRunner::notifyScriptReady fails to find scriptElement and we are left with a null entry in
+ m_scriptsToExecuteSoon. However I haven't managed to repro this or find the exact path how this
+ could happen. The related code is fragile with lot of state (in ScriptElement class)
+ and involves many opportunities for re-entry via scripts.
+
+ No repro, no test case.
+
+ * dom/ScriptRunner.cpp:
+ (WebCore::ScriptRunner::timerFired):
+
+ Paper this over by adding a null check. We could check m_pendingAsyncScripts.take() above
+ but this also covers possibility this is caused by something else.
+
</ins><span class="cx"> 2015-04-21 Jinwoo Song <jinwoo7.song@samsung.com>
</span><span class="cx">
</span><span class="cx"> [Cairo] Implement Path::addPath
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit28SourceWebCoredomScriptRunnercpp"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.8/Source/WebCore/dom/ScriptRunner.cpp (184093 => 184094)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.8/Source/WebCore/dom/ScriptRunner.cpp 2015-05-11 13:38:50 UTC (rev 184093)
+++ releases/WebKitGTK/webkit-2.8/Source/WebCore/dom/ScriptRunner.cpp 2015-05-11 13:41:28 UTC (rev 184094)
</span><span class="lines">@@ -113,6 +113,10 @@
</span><span class="cx"> for (size_t i = 0; i < size; ++i) {
</span><span class="cx"> CachedScript* cachedScript = scripts[i].cachedScript();
</span><span class="cx"> RefPtr<Element> element = scripts[i].releaseElementAndClear();
</span><ins>+ ASSERT(element);
+ // Paper over https://bugs.webkit.org/show_bug.cgi?id=144050
+ if (!element)
+ continue;
</ins><span class="cx"> toScriptElementIfPossible(element.get())->execute(cachedScript);
</span><span class="cx"> m_document.decrementLoadEventDelayCount();
</span><span class="cx"> }
</span></span></pre>
</div>
</div>
</body>
</html>