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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/204620">204620</a></dd>
<dt>Author</dt> <dd>commit-queue@webkit.org</dd>
<dt>Date</dt> <dd>2016-08-18 18:01:47 -0700 (Thu, 18 Aug 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>Binding NULL pointer to reference in WebCore::RenderObject
https://bugs.webkit.org/show_bug.cgi?id=160830
Patch by Jonathan Bedard <jbedard@apple.com> on 2016-08-18
Reviewed by Myles C. Maxfield.
No new tests needed, existing functionality not changed.
Fixes a dereferenced NULL pointer bound to a reference through a minor re-factor.
* rendering/InlineIterator.h:
(WebCore::InlineIterator::clear): Explicit clear occurs, instead of a call to moveTo.
(WebCore::InlineIterator::moveToStartOf): Swapped pointer for reference.
(WebCore::InlineIterator::moveTo): Swapped pointer for reference.
(WebCore::InlineIterator::increment): Explicitly call clear for clarity.
* rendering/line/BreakingContext.h:
(WebCore::BreakingContext::commitLineBreakClear): Commit a line break and clear the iterator.
(WebCore::BreakingContext::commitLineBreakAtCurrentWidth): Swapped pointer for reference.
(WebCore::BreakingContext::InlineIteratorHistory::moveTo): Swapped pointer for reference.
(WebCore::BreakingContext::increment): Explicitly call clear for clarity.
(WebCore::BreakingContext::handleBR): Swapped pointer for passed reference.
(WebCore::BreakingContext::handleReplaced): Explicitly call clear for clarity.
(WebCore::tryHyphenating): Swapped pointer for passed reference.
(WebCore::BreakingContext::handleText): Replaced all render object passing with references. Note that the caller explicitly checks if m_current.renderer() exists before calling this function.
(WebCore::BreakingContext::commitAndUpdateLineBreakIfNeeded): Explicitly call clear for clarity.
(WebCore::BreakingContext::handleEndOfLine): Explicitly call clear for clarity.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceWebCoreChangeLog">trunk/Source/WebCore/ChangeLog</a></li>
<li><a href="#trunkSourceWebCorerenderingInlineIteratorh">trunk/Source/WebCore/rendering/InlineIterator.h</a></li>
<li><a href="#trunkSourceWebCorerenderinglineBreakingContexth">trunk/Source/WebCore/rendering/line/BreakingContext.h</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/ChangeLog (204619 => 204620)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/ChangeLog 2016-08-19 00:55:42 UTC (rev 204619)
+++ trunk/Source/WebCore/ChangeLog 2016-08-19 01:01:47 UTC (rev 204620)
</span><span class="lines">@@ -1,3 +1,31 @@
</span><ins>+2016-08-18 Jonathan Bedard <jbedard@apple.com>
+
+ Binding NULL pointer to reference in WebCore::RenderObject
+ https://bugs.webkit.org/show_bug.cgi?id=160830
+
+ Reviewed by Myles C. Maxfield.
+
+ No new tests needed, existing functionality not changed.
+
+ Fixes a dereferenced NULL pointer bound to a reference through a minor re-factor.
+
+ * rendering/InlineIterator.h:
+ (WebCore::InlineIterator::clear): Explicit clear occurs, instead of a call to moveTo.
+ (WebCore::InlineIterator::moveToStartOf): Swapped pointer for reference.
+ (WebCore::InlineIterator::moveTo): Swapped pointer for reference.
+ (WebCore::InlineIterator::increment): Explicitly call clear for clarity.
+ * rendering/line/BreakingContext.h:
+ (WebCore::BreakingContext::commitLineBreakClear): Commit a line break and clear the iterator.
+ (WebCore::BreakingContext::commitLineBreakAtCurrentWidth): Swapped pointer for reference.
+ (WebCore::BreakingContext::InlineIteratorHistory::moveTo): Swapped pointer for reference.
+ (WebCore::BreakingContext::increment): Explicitly call clear for clarity.
+ (WebCore::BreakingContext::handleBR): Swapped pointer for passed reference.
+ (WebCore::BreakingContext::handleReplaced): Explicitly call clear for clarity.
+ (WebCore::tryHyphenating): Swapped pointer for passed reference.
+ (WebCore::BreakingContext::handleText): Replaced all render object passing with references. Note that the caller explicitly checks if m_current.renderer() exists before calling this function.
+ (WebCore::BreakingContext::commitAndUpdateLineBreakIfNeeded): Explicitly call clear for clarity.
+ (WebCore::BreakingContext::handleEndOfLine): Explicitly call clear for clarity.
+
</ins><span class="cx"> 2016-08-18 Ryosuke Niwa <rniwa@webkit.org>
</span><span class="cx">
</span><span class="cx"> Windows build fix after r204611. Use the fully qualified name to avoid the ambiguity in VC++.
</span></span></pre></div>
<a id="trunkSourceWebCorerenderingInlineIteratorh"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/rendering/InlineIterator.h (204619 => 204620)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/rendering/InlineIterator.h 2016-08-19 00:55:42 UTC (rev 204619)
+++ trunk/Source/WebCore/rendering/InlineIterator.h 2016-08-19 01:01:47 UTC (rev 204620)
</span><span class="lines">@@ -64,16 +64,20 @@
</span><span class="cx"> {
</span><span class="cx"> }
</span><span class="cx">
</span><del>- void clear() { moveTo(nullptr, 0); }
-
- void moveToStartOf(RenderObject* object)
</del><ins>+ void clear()
</ins><span class="cx"> {
</span><ins>+ setRenderer(nullptr);
+ setOffset(0);
+ setNextBreakablePosition(-1);
+ }
+ void moveToStartOf(RenderObject& object)
+ {
</ins><span class="cx"> moveTo(object, 0);
</span><span class="cx"> }
</span><span class="cx">
</span><del>- void moveTo(RenderObject* object, unsigned offset, Optional<unsigned> nextBreak = Nullopt)
</del><ins>+ void moveTo(RenderObject& object, unsigned offset, Optional<unsigned> nextBreak = Optional<unsigned>())
</ins><span class="cx"> {
</span><del>- setRenderer(object);
</del><ins>+ setRenderer(&object);
</ins><span class="cx"> setOffset(offset);
</span><span class="cx"> setNextBreakablePosition(nextBreak);
</span><span class="cx"> }
</span><span class="lines">@@ -397,8 +401,12 @@
</span><span class="cx"> if (m_pos < downcast<RenderText>(*m_renderer).textLength())
</span><span class="cx"> return;
</span><span class="cx"> }
</span><del>- // bidiNext can return nullptr, so use moveTo instead of moveToStartOf
- moveTo(bidiNextSkippingEmptyInlines(*m_root, m_renderer, resolver), 0);
</del><ins>+ // bidiNext can return nullptr
+ RenderObject* bidiNext = bidiNextSkippingEmptyInlines(*m_root, m_renderer, resolver);
+ if (bidiNext)
+ moveToStartOf(*bidiNext);
+ else
+ clear();
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> inline void InlineIterator::fastDecrement()
</span></span></pre></div>
<a id="trunkSourceWebCorerenderinglineBreakingContexth"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/rendering/line/BreakingContext.h (204619 => 204620)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/rendering/line/BreakingContext.h 2016-08-19 00:55:42 UTC (rev 204619)
+++ trunk/Source/WebCore/rendering/line/BreakingContext.h 2016-08-19 01:01:47 UTC (rev 204620)
</span><span class="lines">@@ -166,13 +166,20 @@
</span><span class="cx"> m_hangsAtEnd = false;
</span><span class="cx"> }
</span><span class="cx">
</span><del>- void commitLineBreakAtCurrentWidth(RenderObject& object, unsigned offset = 0, Optional<unsigned> nextBreak = Nullopt)
</del><ins>+ void commitLineBreakClear()
</ins><span class="cx"> {
</span><span class="cx"> m_width.commit();
</span><del>- m_lineBreakHistory.moveTo(&object, offset, nextBreak);
</del><ins>+ m_lineBreakHistory.clear();
</ins><span class="cx"> m_hangsAtEnd = false;
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+ void commitLineBreakAtCurrentWidth(RenderObject& object, unsigned offset = 0, Optional<unsigned> nextBreak = Optional<unsigned>())
+ {
+ m_width.commit();
+ m_lineBreakHistory.moveTo(object, offset, nextBreak);
+ m_hangsAtEnd = false;
+ }
+
</ins><span class="cx"> private:
</span><span class="cx"> // This class keeps a sliding window of the past n locations for an InlineIterator.
</span><span class="cx"> class InlineIteratorHistory : private Vector<InlineIterator, 1> {
</span><span class="lines">@@ -210,7 +217,7 @@
</span><span class="cx"> const InlineIterator& current() const { return get(0); }
</span><span class="cx"> size_t historyLength() const { return this->size(); }
</span><span class="cx">
</span><del>- void moveTo(RenderObject* object, unsigned offset, Optional<unsigned> nextBreak = Nullopt)
</del><ins>+ void moveTo(RenderObject& object, unsigned offset, Optional<unsigned> nextBreak = Nullopt)
</ins><span class="cx"> {
</span><span class="cx"> push([&](InlineIterator& modifyMe) {
</span><span class="cx"> modifyMe.moveTo(object, offset, nextBreak);
</span><span class="lines">@@ -326,7 +333,10 @@
</span><span class="cx"> if (!m_collapseWhiteSpace)
</span><span class="cx"> m_currentCharacterIsSpace = false;
</span><span class="cx">
</span><del>- m_current.moveToStartOf(m_nextObject);
</del><ins>+ if (m_nextObject)
+ m_current.moveToStartOf(*m_nextObject);
+ else
+ m_current.clear();
</ins><span class="cx"> m_atStart = false;
</span><span class="cx"> }
</span><span class="cx">
</span><span class="lines">@@ -335,7 +345,7 @@
</span><span class="cx"> if (fitsOnLineOrHangsAtEnd()) {
</span><span class="cx"> RenderObject& br = *m_current.renderer();
</span><span class="cx"> m_lineBreakHistory.push([&](InlineIterator& modifyMe) {
</span><del>- modifyMe.moveToStartOf(&br);
</del><ins>+ modifyMe.moveToStartOf(br);
</ins><span class="cx"> modifyMe.increment();
</span><span class="cx"> });
</span><span class="cx">
</span><span class="lines">@@ -533,7 +543,10 @@
</span><span class="cx"> // Break on replaced elements if either has normal white-space.
</span><span class="cx"> if (((m_autoWrap || RenderStyle::autoWrap(m_lastWS)) && (!m_current.renderer()->isImage() || m_allowImagesToBreak)
</span><span class="cx"> && (!m_current.renderer()->isRubyRun() || downcast<RenderRubyRun>(m_current.renderer())->canBreakBefore(m_renderTextInfo.lineBreakIterator))) || replacedBox.isAnonymousInlineBlock()) {
</span><del>- commitLineBreakAtCurrentWidth(*m_current.renderer());
</del><ins>+ if (auto* renderer = m_current.renderer())
+ commitLineBreakAtCurrentWidth(*renderer);
+ else
+ commitLineBreakClear();
</ins><span class="cx"> if (m_width.committedWidth() && replacedBox.isAnonymousInlineBlock()) {
</span><span class="cx"> // Always force a break before an anonymous inline block if there is content on the line
</span><span class="cx"> // already.
</span><span class="lines">@@ -713,7 +726,7 @@
</span><span class="cx"> UNUSED_PARAM(isFixedPitch);
</span><span class="cx"> #endif
</span><span class="cx">
</span><del>- lineBreak.moveTo(&text, lastSpace + prefixLength, nextBreakable);
</del><ins>+ lineBreak.moveTo(text, lastSpace + prefixLength, nextBreakable);
</ins><span class="cx"> hyphenated = true;
</span><span class="cx"> }
</span><span class="cx">
</span><span class="lines">@@ -749,7 +762,8 @@
</span><span class="cx"> if (!m_current.offset())
</span><span class="cx"> m_appliedStartWidth = false;
</span><span class="cx">
</span><del>- RenderText& renderText = downcast<RenderText>(*m_current.renderer());
</del><ins>+ RenderObject& renderObject = *m_current.renderer();
+ RenderText& renderText = downcast<RenderText>(renderObject);
</ins><span class="cx">
</span><span class="cx"> bool isSVGText = renderText.isSVGInlineText();
</span><span class="cx">
</span><span class="lines">@@ -931,7 +945,7 @@
</span><span class="cx"> if (!m_width.fitsOnLineIncludingExtraWidth(charWidth)) {
</span><span class="cx"> lineWasTooWide = true;
</span><span class="cx"> m_lineBreakHistory.push([&](InlineIterator& modifyMe) {
</span><del>- modifyMe.moveTo(m_current.renderer(), m_current.offset(), m_current.nextBreakablePosition());
</del><ins>+ modifyMe.moveTo(renderObject, m_current.offset(), m_current.nextBreakablePosition());
</ins><span class="cx"> m_lineBreaker.skipTrailingWhitespace(modifyMe, m_lineInfo);
</span><span class="cx"> });
</span><span class="cx"> }
</span><span class="lines">@@ -1008,7 +1022,7 @@
</span><span class="cx"> if (c == '\n' && m_preservesNewline) {
</span><span class="cx"> if (!stoppedIgnoringSpaces && m_current.offset())
</span><span class="cx"> ensureCharacterGetsLineBox(m_lineWhitespaceCollapsingState, m_current);
</span><del>- commitLineBreakAtCurrentWidth(*m_current.renderer(), m_current.offset(), m_current.nextBreakablePosition());
</del><ins>+ commitLineBreakAtCurrentWidth(renderObject, m_current.offset(), m_current.nextBreakablePosition());
</ins><span class="cx"> m_lineBreakHistory.increment();
</span><span class="cx"> m_lineInfo.setPreviousLineBrokeCleanly(true);
</span><span class="cx"> return true;
</span><span class="lines">@@ -1015,7 +1029,7 @@
</span><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> if (m_autoWrap && betweenWords) {
</span><del>- commitLineBreakAtCurrentWidth(*m_current.renderer(), m_current.offset(), m_current.nextBreakablePosition());
</del><ins>+ commitLineBreakAtCurrentWidth(renderObject, m_current.offset(), m_current.nextBreakablePosition());
</ins><span class="cx"> wrapW = 0;
</span><span class="cx"> // Auto-wrapping text should not wrap in the middle of a word once it has had an
</span><span class="cx"> // opportunity to break after a word.
</span><span class="lines">@@ -1025,7 +1039,7 @@
</span><span class="cx"> if (midWordBreak && !U16_IS_TRAIL(c) && !(U_GET_GC_MASK(c) & U_GC_M_MASK)) {
</span><span class="cx"> // Remember this as a breakable position in case
</span><span class="cx"> // adding the end width forces a break.
</span><del>- m_lineBreakHistory.moveTo(m_current.renderer(), m_current.offset(), m_current.nextBreakablePosition());
</del><ins>+ m_lineBreakHistory.moveTo(renderObject, m_current.offset(), m_current.nextBreakablePosition());
</ins><span class="cx"> midWordBreak &= (breakWords || breakAll);
</span><span class="cx"> }
</span><span class="cx">
</span><span class="lines">@@ -1085,7 +1099,7 @@
</span><span class="cx">
</span><span class="cx"> if (!m_currentCharacterIsWS && previousCharacterIsWS) {
</span><span class="cx"> if (m_autoWrap && m_currentStyle->breakOnlyAfterWhiteSpace())
</span><del>- m_lineBreakHistory.moveTo(m_current.renderer(), m_current.offset(), m_current.nextBreakablePosition());
</del><ins>+ m_lineBreakHistory.moveTo(renderObject, m_current.offset(), m_current.nextBreakablePosition());
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> if (m_collapseWhiteSpace && m_currentCharacterIsSpace && !m_ignoringSpaces)
</span><span class="lines">@@ -1223,8 +1237,12 @@
</span><span class="cx">
</span><span class="cx"> if (!m_current.renderer()->isFloatingOrOutOfFlowPositioned()) {
</span><span class="cx"> m_lastObject = m_current.renderer();
</span><del>- if (m_lastObject->isReplaced() && m_autoWrap && !m_lastObject->isRubyRun() && (!m_lastObject->isImage() || m_allowImagesToBreak) && (!is<RenderListMarker>(*m_lastObject) || downcast<RenderListMarker>(*m_lastObject).isInside()))
- commitLineBreakAtCurrentWidth(*m_nextObject);
</del><ins>+ if (m_lastObject->isReplaced() && m_autoWrap && !m_lastObject->isRubyRun() && (!m_lastObject->isImage() || m_allowImagesToBreak) && (!is<RenderListMarker>(*m_lastObject) || downcast<RenderListMarker>(*m_lastObject).isInside())) {
+ if (m_nextObject)
+ commitLineBreakAtCurrentWidth(*m_nextObject);
+ else
+ commitLineBreakClear();
+ }
</ins><span class="cx"> }
</span><span class="cx"> }
</span><span class="cx">
</span><span class="lines">@@ -1257,8 +1275,12 @@
</span><span class="cx"> if (m_lineBreakHistory.current() == m_resolver.position()) {
</span><span class="cx"> if (!m_lineBreakHistory.renderer() || !m_lineBreakHistory.renderer()->isBR()) {
</span><span class="cx"> // we just add as much as possible
</span><del>- if (m_blockStyle.whiteSpace() == PRE && !m_current.offset())
- commitLineBreakAtCurrentWidth(*m_lastObject, m_lastObject->isText() ? m_lastObject->length() : 0);
</del><ins>+ if (m_blockStyle.whiteSpace() == PRE && !m_current.offset()) {
+ if (m_lastObject)
+ commitLineBreakAtCurrentWidth(*m_lastObject, m_lastObject->isText() ? m_lastObject->length() : 0);
+ else
+ commitLineBreakClear();
+ }
</ins><span class="cx"> else if (m_lineBreakHistory.renderer()) {
</span><span class="cx"> // Don't ever break in the middle of a word if we can help it.
</span><span class="cx"> // There's no room at all. We just have to be on this line,
</span></span></pre>
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