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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/192722">192722</a></dd>
<dt>Author</dt> <dd>akling@apple.com</dd>
<dt>Date</dt> <dd>2015-11-20 22:07:40 -0800 (Fri, 20 Nov 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>REGRESSION(<a href="http://trac.webkit.org/projects/webkit/changeset/192536">r192536</a>): Null pointer dereference in JSPropertyNameEnumerator::visitChildren().
<https://webkit.org/b/151495>
Reviewed by Mark Lam.
Source/JavaScriptCore:
The copied space allocation in JSPropertyNameEnumerator::finishCreation()
may end up triggering a GC, and so JSPropertyNameEnumerator::visitChildren()
would get called while m_propertyNames was still null.
This patch fixes that by having visitChildren() check for pointer nullity
instead of the number of names, since that is non-zero even before the
allocation is made.
Added a test that induces GC during JSPropertyNameEnumerator construction
to cover this bug.
Test: property-name-enumerator-gc-151495.js
* runtime/JSPropertyNameEnumerator.cpp:
(JSC::JSPropertyNameEnumerator::visitChildren):
LayoutTests:
* js/property-name-enumerator-gc-151495.html: Added.
* js/property-name-enumerator-gc-151495-expected.txt: Added.
* js/script-tests/property-name-enumerator-gc-151495.js: Added.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkLayoutTestsChangeLog">trunk/LayoutTests/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreruntimeJSPropertyNameEnumeratorcpp">trunk/Source/JavaScriptCore/runtime/JSPropertyNameEnumerator.cpp</a></li>
</ul>
<h3>Added Paths</h3>
<ul>
<li><a href="#trunkLayoutTestsjspropertynameenumeratorgc151495expectedtxt">trunk/LayoutTests/js/property-name-enumerator-gc-151495-expected.txt</a></li>
<li><a href="#trunkLayoutTestsjspropertynameenumeratorgc151495html">trunk/LayoutTests/js/property-name-enumerator-gc-151495.html</a></li>
<li><a href="#trunkLayoutTestsjsscripttestspropertynameenumeratorgc151495js">trunk/LayoutTests/js/script-tests/property-name-enumerator-gc-151495.js</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkLayoutTestsChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/LayoutTests/ChangeLog (192721 => 192722)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/ChangeLog 2015-11-21 04:40:40 UTC (rev 192721)
+++ trunk/LayoutTests/ChangeLog 2015-11-21 06:07:40 UTC (rev 192722)
</span><span class="lines">@@ -1,3 +1,14 @@
</span><ins>+2015-11-20 Andreas Kling <akling@apple.com>
+
+ REGRESSION(r192536): Null pointer dereference in JSPropertyNameEnumerator::visitChildren().
+ <https://webkit.org/b/151495>
+
+ Reviewed by Mark Lam.
+
+ * js/property-name-enumerator-gc-151495.html: Added.
+ * js/property-name-enumerator-gc-151495-expected.txt: Added.
+ * js/script-tests/property-name-enumerator-gc-151495.js: Added.
+
</ins><span class="cx"> 2015-11-20 Brady Eidson <beidson@apple.com>
</span><span class="cx">
</span><span class="cx"> Modern IDB: After versionchange transactions complete, fire onsuccess on the original IDBOpenDBRequest
</span></span></pre></div>
<a id="trunkLayoutTestsjspropertynameenumeratorgc151495expectedtxt"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/js/property-name-enumerator-gc-151495-expected.txt (0 => 192722)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/js/property-name-enumerator-gc-151495-expected.txt (rev 0)
+++ trunk/LayoutTests/js/property-name-enumerator-gc-151495-expected.txt 2015-11-21 06:07:40 UTC (rev 192722)
</span><span class="lines">@@ -0,0 +1,9 @@
</span><ins>+Regression test for https://webkit.org/b/151495. - This test should not crash.
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS successfullyParsed is true
+
+TEST COMPLETE
+
</ins></span></pre></div>
<a id="trunkLayoutTestsjspropertynameenumeratorgc151495html"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/js/property-name-enumerator-gc-151495.html (0 => 192722)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/js/property-name-enumerator-gc-151495.html (rev 0)
+++ trunk/LayoutTests/js/property-name-enumerator-gc-151495.html 2015-11-21 06:07:40 UTC (rev 192722)
</span><span class="lines">@@ -0,0 +1,10 @@
</span><ins>+<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
+<html>
+<head>
+<script src="../resources/js-test-pre.js"></script>
+</head>
+<body>
+<script src="script-tests/property-name-enumerator-gc-151495.js"></script>
+<script src="../resources/js-test-post.js"></script>
+</body>
+</html>
</ins></span></pre></div>
<a id="trunkLayoutTestsjsscripttestspropertynameenumeratorgc151495js"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/js/script-tests/property-name-enumerator-gc-151495.js (0 => 192722)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/js/script-tests/property-name-enumerator-gc-151495.js (rev 0)
+++ trunk/LayoutTests/js/script-tests/property-name-enumerator-gc-151495.js 2015-11-21 06:07:40 UTC (rev 192722)
</span><span class="lines">@@ -0,0 +1,9 @@
</span><ins>+description("Regression test for https://webkit.org/b/151495. - This test should not crash.");
+
+var x = { a: 1, b: 2, c: 3, d: 4, e: 5, f: 6 };
+for (i = 0; i < 2000; ++i) {
+ // Keep adding new properties...
+ x["foo" + i] = 1;
+ // ...to force creation of new JSPropertyNameEnumerator objects.
+ for (j in x) { }
+}
</ins></span></pre></div>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (192721 => 192722)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2015-11-21 04:40:40 UTC (rev 192721)
+++ trunk/Source/JavaScriptCore/ChangeLog 2015-11-21 06:07:40 UTC (rev 192722)
</span><span class="lines">@@ -1,5 +1,28 @@
</span><span class="cx"> 2015-11-20 Andreas Kling <akling@apple.com>
</span><span class="cx">
</span><ins>+ REGRESSION(r192536): Null pointer dereference in JSPropertyNameEnumerator::visitChildren().
+ <https://webkit.org/b/151495>
+
+ Reviewed by Mark Lam.
+
+ The copied space allocation in JSPropertyNameEnumerator::finishCreation()
+ may end up triggering a GC, and so JSPropertyNameEnumerator::visitChildren()
+ would get called while m_propertyNames was still null.
+
+ This patch fixes that by having visitChildren() check for pointer nullity
+ instead of the number of names, since that is non-zero even before the
+ allocation is made.
+
+ Added a test that induces GC during JSPropertyNameEnumerator construction
+ to cover this bug.
+
+ Test: property-name-enumerator-gc-151495.js
+
+ * runtime/JSPropertyNameEnumerator.cpp:
+ (JSC::JSPropertyNameEnumerator::visitChildren):
+
+2015-11-20 Andreas Kling <akling@apple.com>
+
</ins><span class="cx"> GC timers should carry on gracefully when Heap claims it grew from GC.
</span><span class="cx"> <https://webkit.org/b/151521>
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreruntimeJSPropertyNameEnumeratorcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/runtime/JSPropertyNameEnumerator.cpp (192721 => 192722)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/runtime/JSPropertyNameEnumerator.cpp 2015-11-21 04:40:40 UTC (rev 192721)
+++ trunk/Source/JavaScriptCore/runtime/JSPropertyNameEnumerator.cpp 2015-11-21 06:07:40 UTC (rev 192722)
</span><span class="lines">@@ -89,12 +89,12 @@
</span><span class="cx"> JSPropertyNameEnumerator* thisObject = jsCast<JSPropertyNameEnumerator*>(cell);
</span><span class="cx"> visitor.append(&thisObject->m_prototypeChain);
</span><span class="cx">
</span><del>- if (thisObject->cachedPropertyNameCount()) {
</del><ins>+ if (auto* propertyNames = thisObject->m_propertyNames.getWithoutBarrier()) {
</ins><span class="cx"> for (unsigned i = 0; i < thisObject->cachedPropertyNameCount(); ++i)
</span><del>- visitor.append(&thisObject->m_propertyNames.getWithoutBarrier()[i]);
</del><ins>+ visitor.append(&propertyNames[i]);
</ins><span class="cx"> visitor.copyLater(
</span><span class="cx"> thisObject, JSPropertyNameEnumeratorCopyToken,
</span><del>- thisObject->m_propertyNames.getWithoutBarrier(), thisObject->propertyNameCacheSize());
</del><ins>+ propertyNames, thisObject->propertyNameCacheSize());
</ins><span class="cx"> }
</span><span class="cx"> }
</span><span class="cx">
</span></span></pre>
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