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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/186840">186840</a></dd>
<dt>Author</dt> <dd>commit-queue@webkit.org</dd>
<dt>Date</dt> <dd>2015-07-15 09:02:39 -0700 (Wed, 15 Jul 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>Negative scroll snap repeat values cause web process to hang indefinitely
https://bugs.webkit.org/show_bug.cgi?id=146953
Source/WebCore:
<rdar://problem/21823681>
Patch by Wenson Hsieh <wenson_hsieh@apple.com> on 2015-07-15
Reviewed by Simon Fraser.
Fixed dangerous behavior caused by setting -scroll-snap-points-x or -y to negative or very small
positive values. In the case of negative or 0 repeats, the web process would hang indefinitely. In
the case of very small positive values, a massive amount of memory could potentially be allocated
just to store snap offsets.
Tests: css3/scroll-snap/scroll-snap-negative-repeat.html
css3/scroll-snap/scroll-snap-subpixel-repeat.html
* css/CSSParser.cpp:
(WebCore::CSSParser::parseNonElementSnapPoints): Changed to consider negative snap repeat values as invalid CSS.
* page/scrolling/AxisScrollSnapOffsets.cpp:
(WebCore::updateFromStyle): Changed to threshold non-negative snap repeat values to 1px.
LayoutTests:
Patch by Wenson Hsieh <wenson_hsieh@apple.com> on 2015-07-15
Reviewed by Simon Fraser.
The first test case checks that setting -scroll-snap-points-x or -y to a negative value
will not cause the web process to hang. The second test case (in a similar vein) checks
that tiny subpixel snap repeats generate a reasonable number of snap offsets.
* css3/scroll-snap/scroll-snap-negative-repeat-expected.txt: Added.
* css3/scroll-snap/scroll-snap-negative-repeat.html: Added.
* css3/scroll-snap/scroll-snap-subpixel-repeat-expected.txt: Added.
* css3/scroll-snap/scroll-snap-subpixel-repeat.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="#trunkSourceWebCorecssCSSParsercpp">trunk/Source/WebCore/css/CSSParser.cpp</a></li>
<li><a href="#trunkSourceWebCorepagescrollingAxisScrollSnapOffsetscpp">trunk/Source/WebCore/page/scrolling/AxisScrollSnapOffsets.cpp</a></li>
</ul>
<h3>Added Paths</h3>
<ul>
<li><a href="#trunkLayoutTestscss3scrollsnapscrollsnapnegativerepeatexpectedtxt">trunk/LayoutTests/css3/scroll-snap/scroll-snap-negative-repeat-expected.txt</a></li>
<li><a href="#trunkLayoutTestscss3scrollsnapscrollsnapnegativerepeathtml">trunk/LayoutTests/css3/scroll-snap/scroll-snap-negative-repeat.html</a></li>
<li><a href="#trunkLayoutTestscss3scrollsnapscrollsnapsubpixelrepeatexpectedtxt">trunk/LayoutTests/css3/scroll-snap/scroll-snap-subpixel-repeat-expected.txt</a></li>
<li><a href="#trunkLayoutTestscss3scrollsnapscrollsnapsubpixelrepeathtml">trunk/LayoutTests/css3/scroll-snap/scroll-snap-subpixel-repeat.html</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkLayoutTestsChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/LayoutTests/ChangeLog (186839 => 186840)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/ChangeLog 2015-07-15 16:01:32 UTC (rev 186839)
+++ trunk/LayoutTests/ChangeLog 2015-07-15 16:02:39 UTC (rev 186840)
</span><span class="lines">@@ -1,3 +1,19 @@
</span><ins>+2015-07-15 Wenson Hsieh <wenson_hsieh@apple.com>
+
+ Negative scroll snap repeat values cause web process to hang indefinitely
+ https://bugs.webkit.org/show_bug.cgi?id=146953
+
+ Reviewed by Simon Fraser.
+
+ The first test case checks that setting -scroll-snap-points-x or -y to a negative value
+ will not cause the web process to hang. The second test case (in a similar vein) checks
+ that tiny subpixel snap repeats generate a reasonable number of snap offsets.
+
+ * css3/scroll-snap/scroll-snap-negative-repeat-expected.txt: Added.
+ * css3/scroll-snap/scroll-snap-negative-repeat.html: Added.
+ * css3/scroll-snap/scroll-snap-subpixel-repeat-expected.txt: Added.
+ * css3/scroll-snap/scroll-snap-subpixel-repeat.html: Added.
+
</ins><span class="cx"> 2015-07-15 David Kilzer <ddkilzer@apple.com>
</span><span class="cx">
</span><span class="cx"> http/tests/misc/large-js-program.php crashes slowly in Debug builds on Windows
</span></span></pre></div>
<a id="trunkLayoutTestscss3scrollsnapscrollsnapnegativerepeatexpectedtxt"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/css3/scroll-snap/scroll-snap-negative-repeat-expected.txt (0 => 186840)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/css3/scroll-snap/scroll-snap-negative-repeat-expected.txt (rev 0)
+++ trunk/LayoutTests/css3/scroll-snap/scroll-snap-negative-repeat-expected.txt 2015-07-15 16:02:39 UTC (rev 186840)
</span><span class="lines">@@ -0,0 +1,9 @@
</span><ins>+Tests that negative repeat() values don't hang on snap point computation.
+
+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="trunkLayoutTestscss3scrollsnapscrollsnapnegativerepeathtml"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/css3/scroll-snap/scroll-snap-negative-repeat.html (0 => 186840)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/css3/scroll-snap/scroll-snap-negative-repeat.html (rev 0)
+++ trunk/LayoutTests/css3/scroll-snap/scroll-snap-negative-repeat.html 2015-07-15 16:02:39 UTC (rev 186840)
</span><span class="lines">@@ -0,0 +1,21 @@
</span><ins>+<!DOCTYPE html>
+<html>
+ <head>
+ <style>
+ body {
+ -webkit-scroll-snap-type: mandatory;
+ -webkit-scroll-snap-points-y: repeat(-400px);
+ height: 5000px;
+ }
+ </style>
+ <script src="../../resources/js-test-pre.js"></script>
+ </head>
+ <body>
+ <div id="console"></div>
+ <script>
+ description("Tests that negative repeat() values don't hang on snap point computation.");
+ </script>
+ <script src="../../resources/js-test-post.js"></script>
+ </body>
+</html>
+
</ins></span></pre></div>
<a id="trunkLayoutTestscss3scrollsnapscrollsnapsubpixelrepeatexpectedtxt"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/css3/scroll-snap/scroll-snap-subpixel-repeat-expected.txt (0 => 186840)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/css3/scroll-snap/scroll-snap-subpixel-repeat-expected.txt (rev 0)
+++ trunk/LayoutTests/css3/scroll-snap/scroll-snap-subpixel-repeat-expected.txt 2015-07-15 16:02:39 UTC (rev 186840)
</span><span class="lines">@@ -0,0 +1,13 @@
</span><ins>+Tests that small positive repeat() values generates a reasonable number of snap offsets.
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS successfullyParsed is true
+
+TEST COMPLETE
+Number of snap offsets: 99
+PASS successfullyParsed is true
+
+TEST COMPLETE
+
</ins></span></pre></div>
<a id="trunkLayoutTestscss3scrollsnapscrollsnapsubpixelrepeathtml"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/css3/scroll-snap/scroll-snap-subpixel-repeat.html (0 => 186840)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/css3/scroll-snap/scroll-snap-subpixel-repeat.html (rev 0)
+++ trunk/LayoutTests/css3/scroll-snap/scroll-snap-subpixel-repeat.html 2015-07-15 16:02:39 UTC (rev 186840)
</span><span class="lines">@@ -0,0 +1,71 @@
</span><ins>+<!DOCTYPE html>
+<html>
+ <head>
+ <style>
+ #gallery {
+ height: 100px;
+ width: 100px;
+ overflow-x: hidden;
+ overflow-y: auto;
+ -webkit-scroll-snap-type: mandatory;
+ -webkit-scroll-snap-points-y: repeat(0.0001px);
+ margin: 0;
+ padding: 0;
+ }
+
+ .colorBox {
+ width: 100px;
+ height: 100px;
+ }
+
+ #item0 { background-color: red; }
+ #item1 { background-color: green; }
+ </style>
+ <script src="../../resources/js-test-pre.js"></script>
+ <script>
+ function runTest()
+ {
+ var gallery = document.getElementById("gallery");
+
+ if (window.testRunner) {
+ window.jsTestIsAsync = true;
+ testRunner.dumpAsText();
+ testRunner.waitUntilDone();
+ setTimeout(dumpSnapOffsets, 0);
+ }
+
+ function snapOffsetsFromString(offsetsAsString)
+ {
+ var startIndex = offsetsAsString.search(/\{/);
+ var endIndex = offsetsAsString.search(/\}/);
+ if (startIndex == -1 || endIndex == -1 || endIndex <= startIndex)
+ return []
+
+ return offsetsAsString
+ .substring(startIndex + 1, endIndex - startIndex - 1)
+ .trim()
+ .split(",")
+ .map(function(s) { return parseFloat(s.trim()) });
+ }
+
+ function dumpSnapOffsets()
+ {
+ var offsets = snapOffsetsFromString(window.internals.scrollSnapOffsets(gallery));
+ debug("Number of snap offsets: " + offsets.length);
+ finishJSTest();
+ }
+ }
+ </script>
+ </head>
+ <body onload="runTest()">
+ <div id="gallery">
+ <div id="item0" class="colorBox"></div>
+ <div id="item1" class="colorBox"></div>
+ </div>
+ <div id="console"></div>
+ <script>
+ description("Tests that small positive repeat() values generates a reasonable number of snap offsets.");
+ </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 (186839 => 186840)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/ChangeLog 2015-07-15 16:01:32 UTC (rev 186839)
+++ trunk/Source/WebCore/ChangeLog 2015-07-15 16:02:39 UTC (rev 186840)
</span><span class="lines">@@ -1,3 +1,24 @@
</span><ins>+2015-07-15 Wenson Hsieh <wenson_hsieh@apple.com>
+
+ Negative scroll snap repeat values cause web process to hang indefinitely
+ https://bugs.webkit.org/show_bug.cgi?id=146953
+ <rdar://problem/21823681>
+
+ Reviewed by Simon Fraser.
+
+ Fixed dangerous behavior caused by setting -scroll-snap-points-x or -y to negative or very small
+ positive values. In the case of negative or 0 repeats, the web process would hang indefinitely. In
+ the case of very small positive values, a massive amount of memory could potentially be allocated
+ just to store snap offsets.
+
+ Tests: css3/scroll-snap/scroll-snap-negative-repeat.html
+ css3/scroll-snap/scroll-snap-subpixel-repeat.html
+
+ * css/CSSParser.cpp:
+ (WebCore::CSSParser::parseNonElementSnapPoints): Changed to consider negative snap repeat values as invalid CSS.
+ * page/scrolling/AxisScrollSnapOffsets.cpp:
+ (WebCore::updateFromStyle): Changed to threshold non-negative snap repeat values to 1px.
+
</ins><span class="cx"> 2015-07-14 Dean Jackson <dino@apple.com>
</span><span class="cx">
</span><span class="cx"> Placeholder colors should be system grays
</span></span></pre></div>
<a id="trunkSourceWebCorecssCSSParsercpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/css/CSSParser.cpp (186839 => 186840)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/css/CSSParser.cpp 2015-07-15 16:01:32 UTC (rev 186839)
+++ trunk/Source/WebCore/css/CSSParser.cpp 2015-07-15 16:02:39 UTC (rev 186840)
</span><span class="lines">@@ -3397,7 +3397,7 @@
</span><span class="cx"> && value->function->args->size() == 1
</span><span class="cx"> && equalIgnoringCase(value->function->name, "repeat(")) {
</span><span class="cx"> ValueWithCalculation argumentWithCalculation(*value->function->args.get()->current());
</span><del>- if (validateUnit(argumentWithCalculation, FLength | FPercent)) {
</del><ins>+ if (validateUnit(argumentWithCalculation, FLength | FPercent | FNonNeg)) {
</ins><span class="cx"> values->append(cssValuePool().createValue(LengthRepeat::create(createPrimitiveNumericValue(argumentWithCalculation))));
</span><span class="cx"> m_valueList->next();
</span><span class="cx"> if (m_valueList->current())
</span></span></pre></div>
<a id="trunkSourceWebCorepagescrollingAxisScrollSnapOffsetscpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/page/scrolling/AxisScrollSnapOffsets.cpp (186839 => 186840)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/page/scrolling/AxisScrollSnapOffsets.cpp 2015-07-15 16:01:32 UTC (rev 186839)
+++ trunk/Source/WebCore/page/scrolling/AxisScrollSnapOffsets.cpp 2015-07-15 16:02:39 UTC (rev 186840)
</span><span class="lines">@@ -87,7 +87,9 @@
</span><span class="cx">
</span><span class="cx"> auto* points = (axis == ScrollEventAxis::Horizontal) ? style.scrollSnapPointsX() : style.scrollSnapPointsY();
</span><span class="cx"> bool hasRepeat = points ? points->hasRepeat : false;
</span><del>- LayoutUnit repeatOffset = points ? valueForLength(points->repeatOffset, viewSize) : LayoutUnit();
</del><ins>+ LayoutUnit repeatOffset = points ? valueForLength(points->repeatOffset, viewSize) : LayoutUnit::fromPixel(1);
+ repeatOffset = std::max<LayoutUnit>(repeatOffset, LayoutUnit::fromPixel(1));
+
</ins><span class="cx"> LayoutUnit destinationOffset = destinationOffsetForViewSize(axis, style.scrollSnapDestination(), viewSize);
</span><span class="cx"> LayoutUnit curSnapPositionShift = 0;
</span><span class="cx"> LayoutUnit maxScrollOffset = scrollSize - viewSize;
</span></span></pre>
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