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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/203083">203083</a></dd>
<dt>Author</dt> <dd>n_wang@apple.com</dd>
<dt>Date</dt> <dd>2016-07-11 14:04:28 -0700 (Mon, 11 Jul 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>AX: Crash when backspacing in number field with spin button
https://bugs.webkit.org/show_bug.cgi?id=157830
Reviewed by Chris Fleizach.
Source/WebCore:
It's possible to access spin button parts after they've been detached from their parent, which can lead to crashes.
This adds in a number of redundant safeguards to prevent this and other cases in the future.
Test: accessibility/spinbutton-crash.html
* accessibility/AccessibilitySpinButton.cpp:
(WebCore::AccessibilitySpinButton::incrementButton):
(WebCore::AccessibilitySpinButton::decrementButton):
(WebCore::AccessibilitySpinButton::addChildren):
LayoutTests:
* accessibility/spinbutton-crash-expected.txt: Added.
* accessibility/spinbutton-crash.html: Added.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkLayoutTestsChangeLog">trunk/LayoutTests/ChangeLog</a></li>
<li><a href="#trunkSourceWebCoreChangeLog">trunk/Source/WebCore/ChangeLog</a></li>
<li><a href="#trunkSourceWebCoreaccessibilityAccessibilitySpinButtoncpp">trunk/Source/WebCore/accessibility/AccessibilitySpinButton.cpp</a></li>
</ul>
<h3>Added Paths</h3>
<ul>
<li><a href="#trunkLayoutTestsaccessibilityspinbuttoncrashexpectedtxt">trunk/LayoutTests/accessibility/spinbutton-crash-expected.txt</a></li>
<li><a href="#trunkLayoutTestsaccessibilityspinbuttoncrashhtml">trunk/LayoutTests/accessibility/spinbutton-crash.html</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkLayoutTestsChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/LayoutTests/ChangeLog (203082 => 203083)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/ChangeLog 2016-07-11 20:53:48 UTC (rev 203082)
+++ trunk/LayoutTests/ChangeLog 2016-07-11 21:04:28 UTC (rev 203083)
</span><span class="lines">@@ -1,3 +1,13 @@
</span><ins>+2016-07-11 Nan Wang <n_wang@apple.com>
+
+ AX: Crash when backspacing in number field with spin button
+ https://bugs.webkit.org/show_bug.cgi?id=157830
+
+ Reviewed by Chris Fleizach.
+
+ * accessibility/spinbutton-crash-expected.txt: Added.
+ * accessibility/spinbutton-crash.html: Added.
+
</ins><span class="cx"> 2016-07-11 Brent Fulgham <bfulgham@apple.com>
</span><span class="cx">
</span><span class="cx"> [WebGL] Check for existing buffer exists for enabled vertex array attributes before permitting glDrawArrays to execute
</span></span></pre></div>
<a id="trunkLayoutTestsaccessibilityspinbuttoncrashexpectedtxt"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/accessibility/spinbutton-crash-expected.txt (0 => 203083)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/accessibility/spinbutton-crash-expected.txt (rev 0)
+++ trunk/LayoutTests/accessibility/spinbutton-crash-expected.txt 2016-07-11 21:04:28 UTC (rev 203083)
</span><span class="lines">@@ -0,0 +1,14 @@
</span><ins>+
+This tests that a spin button won't access invalid attributes when its already detached.
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+spinner incrementer: AXRole: AXButton
+PASS document.getElementById('number').value is '10'
+PASS document.getElementById('number').value is '5'
+PASS document.getElementById('number').value is ''
+PASS successfullyParsed is true
+
+TEST COMPLETE
+
</ins></span></pre></div>
<a id="trunkLayoutTestsaccessibilityspinbuttoncrashhtml"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/accessibility/spinbutton-crash.html (0 => 203083)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/accessibility/spinbutton-crash.html (rev 0)
+++ trunk/LayoutTests/accessibility/spinbutton-crash.html 2016-07-11 21:04:28 UTC (rev 203083)
</span><span class="lines">@@ -0,0 +1,43 @@
</span><ins>+<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
+<html>
+<head>
+<script src="../resources/js-test-pre.js"></script>
+</head>
+
+<body id="body">
+
+<input type="number" id="number" value="10">
+
+<p id="description"></p>
+<div id="console"></div>
+<script>
+
+ if (window.accessibilityController) {
+ description("This tests that a spin button won't access invalid attributes when its already detached.");
+
+ document.getElementById("number").focus();
+
+ var field = accessibilityController.accessibleElementById("number");
+ var spinner1 = field.childAtIndex(1);
+ var spinnerChild = spinner1.uiElementAttributeValue("AXIncrementButton");
+ debug("spinner incrementer: " + spinnerChild.role);
+
+ shouldBe("document.getElementById('number').value", "'10'");
+ eventSender.keyDown('\u0008');
+ eventSender.keyDown('5');
+ shouldBe("document.getElementById('number').value", "'5'");
+ eventSender.keyDown('\u0008');
+ eventSender.keyDown('\u0008');
+ eventSender.keyDown('\u0008');
+
+ shouldBe("document.getElementById('number').value", "''");
+
+ // Don't crash!
+ var spinnerChild = spinner1.uiElementAttributeValue("AXIncrementButton");
+ }
+ successfullyParsed = true;
+</script>
+
+<script src="../resources/js-test-post.js"></script>
+</body>
+</html>
</ins></span></pre></div>
<a id="trunkSourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/ChangeLog (203082 => 203083)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/ChangeLog 2016-07-11 20:53:48 UTC (rev 203082)
+++ trunk/Source/WebCore/ChangeLog 2016-07-11 21:04:28 UTC (rev 203083)
</span><span class="lines">@@ -1,3 +1,20 @@
</span><ins>+2016-07-11 Nan Wang <n_wang@apple.com>
+
+ AX: Crash when backspacing in number field with spin button
+ https://bugs.webkit.org/show_bug.cgi?id=157830
+
+ Reviewed by Chris Fleizach.
+
+ It's possible to access spin button parts after they've been detached from their parent, which can lead to crashes.
+ This adds in a number of redundant safeguards to prevent this and other cases in the future.
+
+ Test: accessibility/spinbutton-crash.html
+
+ * accessibility/AccessibilitySpinButton.cpp:
+ (WebCore::AccessibilitySpinButton::incrementButton):
+ (WebCore::AccessibilitySpinButton::decrementButton):
+ (WebCore::AccessibilitySpinButton::addChildren):
+
</ins><span class="cx"> 2016-07-11 Chris Dumez <cdumez@apple.com>
</span><span class="cx">
</span><span class="cx"> Possible null dereference under EventHandler::dispatchMouseEvent()
</span></span></pre></div>
<a id="trunkSourceWebCoreaccessibilityAccessibilitySpinButtoncpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/accessibility/AccessibilitySpinButton.cpp (203082 => 203083)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/accessibility/AccessibilitySpinButton.cpp 2016-07-11 20:53:48 UTC (rev 203082)
+++ trunk/Source/WebCore/accessibility/AccessibilitySpinButton.cpp 2016-07-11 21:04:28 UTC (rev 203083)
</span><span class="lines">@@ -49,6 +49,8 @@
</span><span class="cx"> {
</span><span class="cx"> if (!m_haveChildren)
</span><span class="cx"> addChildren();
</span><ins>+ if (!m_haveChildren)
+ return nullptr;
</ins><span class="cx">
</span><span class="cx"> ASSERT(m_children.size() == 2);
</span><span class="cx">
</span><span class="lines">@@ -59,6 +61,8 @@
</span><span class="cx"> {
</span><span class="cx"> if (!m_haveChildren)
</span><span class="cx"> addChildren();
</span><ins>+ if (!m_haveChildren)
+ return nullptr;
</ins><span class="cx">
</span><span class="cx"> ASSERT(m_children.size() == 2);
</span><span class="cx">
</span><span class="lines">@@ -80,14 +84,18 @@
</span><span class="cx">
</span><span class="cx"> void AccessibilitySpinButton::addChildren()
</span><span class="cx"> {
</span><ins>+ AXObjectCache* cache = axObjectCache();
+ if (!cache)
+ return;
+
</ins><span class="cx"> m_haveChildren = true;
</span><span class="cx">
</span><del>- auto& incrementor = downcast<AccessibilitySpinButtonPart>(*axObjectCache()->getOrCreate(SpinButtonPartRole));
</del><ins>+ auto& incrementor = downcast<AccessibilitySpinButtonPart>(*cache->getOrCreate(SpinButtonPartRole));
</ins><span class="cx"> incrementor.setIsIncrementor(true);
</span><span class="cx"> incrementor.setParent(this);
</span><span class="cx"> m_children.append(&incrementor);
</span><span class="cx">
</span><del>- auto& decrementor = downcast<AccessibilitySpinButtonPart>(*axObjectCache()->getOrCreate(SpinButtonPartRole));
</del><ins>+ auto& decrementor = downcast<AccessibilitySpinButtonPart>(*cache->getOrCreate(SpinButtonPartRole));
</ins><span class="cx"> decrementor.setIsIncrementor(false);
</span><span class="cx"> decrementor.setParent(this);
</span><span class="cx"> m_children.append(&decrementor);
</span></span></pre>
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