Bug 118839 – Crash in WTF::RefPtr<WebCore::SpaceSplitStringData>::operator UnspecifiedBoolType

• Component: SVG
• Status: RESOLVED FIXED

[Renata Hodovan]

The following SVG crashes if it's saved as .html file:

<svg xmlns="http://www.w3.org/2000/svg">
   <g>
      <set attributename="class"></set>
   </g>
</svg>


The backtrace: (it seems that m_ptr is a null pointer)

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff3d58938 in WTF::RefPtr<WebCore::SpaceSplitStringData>::operator WebCore::SpaceSplitStringData* WTF::RefPtr<WebCore::SpaceSplitStringData>::* (
    this=0x18) at /home/reni/Data/REPOS/webkit_sec/Source/WTF/wtf/RefPtr.h:76
76	        operator UnspecifiedBoolType() const { return m_ptr ? &RefPtr::m_ptr : 0; }
(gdb) bt
#0  0x00007ffff3d58938 in WTF::RefPtr<WebCore::SpaceSplitStringData>::operator WebCore::SpaceSplitStringData* WTF::RefPtr<WebCore::SpaceSplitStringData>::* (
    this=0x18) at /home/reni/Data/REPOS/webkit_sec/Source/WTF/wtf/RefPtr.h:76
#1  0x00007ffff3d579fe in WebCore::SpaceSplitString::size (this=0x18) at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/dom/SpaceSplitString.h:83
#2  0x00007ffff42f3349 in WebCore::checkSelectorForClassChange<WebCore::StyleResolver> (changedClasses=..., checker=...)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/dom/Element.cpp:1102
#3  0x00007ffff42e95e1 in WebCore::Element::classAttributeChanged (this=0x8a7d80, newClassString=...)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/dom/Element.cpp:1154
#4  0x00007ffff4db00a8 in WebCore::SVGStyledElement::svgAttributeChanged (this=0x8a7d80, attrName=...)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/svg/SVGStyledElement.cpp:333
#5  0x00007ffff4d67588 in WebCore::SVGGraphicsElement::svgAttributeChanged (this=0x8a7d80, attrName=...)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/svg/SVGGraphicsElement.cpp:128
#6  0x00007ffff4d61031 in WebCore::SVGGElement::svgAttributeChanged (this=0x8a7d80, attrName=...)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/svg/SVGGElement.cpp:82
#7  0x00007ffff4d0a1bc in WebCore::notifyTargetAboutAnimValChange (targetElement=0x8a7d80, attributeName=...)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/svg/SVGAnimateElement.cpp:299
#8  0x00007ffff4d0a290 in WebCore::notifyTargetAndInstancesAboutAnimValChange (targetElement=0x8a7d80, attributeName=...)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/svg/SVGAnimateElement.cpp:309
#9  0x00007ffff4d0a61c in WebCore::SVGAnimateElement::applyResultsToTarget (this=0x8b50c0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/svg/SVGAnimateElement.cpp:368
#10 0x00007ffff4cb39aa in WebCore::SMILTimeContainer::updateAnimations (this=0x88bb60, elapsed=..., seekToTime=false)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/svg/animation/SMILTimeContainer.cpp:316
#11 0x00007ffff4cb2cf8 in WebCore::SMILTimeContainer::begin (this=0x88bb60)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/svg/animation/SMILTimeContainer.cpp:139
#12 0x00007ffff4cd7abb in WebCore::SVGDocumentExtensions::startAnimations (this=0x88ddc0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/svg/SVGDocumentExtensions.cpp:102
#13 0x00007ffff42951c3 in WebCore::Document::implicitClose (this=0x873e10) at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/dom/Document.cpp:2478
#14 0x00007ffff4689ec3 in WebCore::FrameLoader::checkCallImplicitClose (this=0x7ad258)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/loader/FrameLoader.cpp:843
#15 0x00007ffff4689c2e in WebCore::FrameLoader::checkCompleted (this=0x7ad258) at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/loader/FrameLoader.cpp:786
#16 0x00007ffff468996c in WebCore::FrameLoader::finishedParsing (this=0x7ad258) at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/loader/FrameLoader.cpp:719
#17 0x00007ffff429c03b in WebCore::Document::finishedParsing (this=0x873e10) at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/dom/Document.cpp:4417
#18 0x00007ffff44e8dd3 in WebCore::HTMLConstructionSite::finishedParsing (this=0x7efaa8)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/html/parser/HTMLConstructionSite.cpp:348
#19 0x00007ffff451a4bf in WebCore::HTMLTreeBuilder::finished (this=0x7efa90)
---Type <return> to continue, or q <return> to quit---
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/html/parser/HTMLTreeBuilder.cpp:2926
#20 0x00007ffff44f0386 in WebCore::HTMLDocumentParser::end (this=0x7676e0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/html/parser/HTMLDocumentParser.cpp:756
#21 0x00007ffff44f0473 in WebCore::HTMLDocumentParser::attemptToRunDeferredScriptsAndEnd (this=0x7676e0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/html/parser/HTMLDocumentParser.cpp:767
#22 0x00007ffff44ef0a6 in WebCore::HTMLDocumentParser::prepareToStopParsing (this=0x7676e0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/html/parser/HTMLDocumentParser.cpp:211
#23 0x00007ffff44f04b6 in WebCore::HTMLDocumentParser::attemptToEnd (this=0x7676e0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/html/parser/HTMLDocumentParser.cpp:779
#24 0x00007ffff44f056d in WebCore::HTMLDocumentParser::finish (this=0x7676e0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/html/parser/HTMLDocumentParser.cpp:828
#25 0x00007ffff46819b5 in WebCore::DocumentWriter::end (this=0x694320) at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/loader/DocumentWriter.cpp:248
#26 0x00007ffff467459e in WebCore::DocumentLoader::finishedLoading (this=0x694280, finishTime=0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/loader/DocumentLoader.cpp:402
#27 0x00007ffff467430c in WebCore::DocumentLoader::notifyFinished (this=0x694280, resource=0x7724a0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/loader/DocumentLoader.cpp:344
#28 0x00007ffff465b9d8 in WebCore::CachedResource::checkNotify (this=0x7724a0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/loader/cache/CachedResource.cpp:369
#29 0x00007ffff465baae in WebCore::CachedResource::finishLoading (this=0x7724a0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/loader/cache/CachedResource.cpp:385
#30 0x00007ffff46581be in WebCore::CachedRawResource::finishLoading (this=0x7724a0, data=0x782aa0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/loader/cache/CachedRawResource.cpp:94
#31 0x00007ffff46bda4a in WebCore::SubresourceLoader::didFinishLoading (this=0x753390, finishTime=0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/loader/SubresourceLoader.cpp:282
#32 0x00007ffff46b43d7 in WebCore::ResourceLoader::didFinishLoading (this=0x753390, finishTime=0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/loader/ResourceLoader.cpp:488
#33 0x00007ffff4b4179c in WebCore::QNetworkReplyHandler::finish (this=0x753fb0)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:516
#34 0x00007ffff4b40462 in WebCore::QNetworkReplyHandlerCallQueue::flush (this=0x753fe8)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:250
#35 0x00007ffff4b4018a in WebCore::QNetworkReplyHandlerCallQueue::push (this=0x753fe8, 
    method=(void (WebCore::QNetworkReplyHandler::*)(WebCore::QNetworkReplyHandler * const)) 0x7ffff4b415de <WebCore::QNetworkReplyHandler::finish()>)
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:216
#36 0x00007ffff4b410e8 in WebCore::QNetworkReplyWrapper::didReceiveFinished (this=0x754360)
---Type <return> to continue, or q <return> to quit---
    at /home/reni/Data/REPOS/webkit_sec/Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:409
#37 0x00007ffff4b43aaa in WebCore::QNetworkReplyWrapper::qt_static_metacall (_o=0x754360, _c=QMetaObject::InvokeMetaMethod, _id=1, _a=0x7fffffffcf80)
    at .moc/release-shared/moc_QNetworkReplyHandler.cpp:176
#38 0x00007ffff231e5cb in QMetaObject::activate(QObject*, int, int, void**) () from /usr/local/Trolltech/Qt5/Qt-5.0.0-r40/lib/libQt5Core.so.5
#39 0x00007ffff231f84e in QObject::event(QEvent*) () from /usr/local/Trolltech/Qt5/Qt-5.0.0-r40/lib/libQt5Core.so.5
#40 0x00007ffff3165dbc in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/local/Trolltech/Qt5/Qt-5.0.0-r40/lib/libQt5Widgets.so.5
#41 0x00007ffff3169075 in QApplication::notify(QObject*, QEvent*) () from /usr/local/Trolltech/Qt5/Qt-5.0.0-r40/lib/libQt5Widgets.so.5
#42 0x00007ffff22f9dbe in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/local/Trolltech/Qt5/Qt-5.0.0-r40/lib/libQt5Core.so.5
#43 0x00007ffff22fba76 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) ()
   from /usr/local/Trolltech/Qt5/Qt-5.0.0-r40/lib/libQt5Core.so.5
#44 0x00007ffff2341333 in ?? () from /usr/local/Trolltech/Qt5/Qt-5.0.0-r40/lib/libQt5Core.so.5
#45 0x00007fffee4840a6 in g_main_dispatch (context=0x6632f0) at /build/buildd/glib2.0-2.37.3/./glib/gmain.c:3058
#46 g_main_context_dispatch (context=context@entry=0x6632f0) at /build/buildd/glib2.0-2.37.3/./glib/gmain.c:3634
#47 0x00007fffee4843f8 in g_main_context_iterate (context=context@entry=0x6632f0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>)
    at /build/buildd/glib2.0-2.37.3/./glib/gmain.c:3705
#48 0x00007fffee48449c in g_main_context_iteration (context=0x6632f0, may_block=1) at /build/buildd/glib2.0-2.37.3/./glib/gmain.c:3766
#49 0x00007ffff23414bc in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
   from /usr/local/Trolltech/Qt5/Qt-5.0.0-r40/lib/libQt5Core.so.5
#50 0x00007ffff22f8d3b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/local/Trolltech/Qt5/Qt-5.0.0-r40/lib/libQt5Core.so.5
#51 0x00007ffff22fc120 in QCoreApplication::exec() () from /usr/local/Trolltech/Qt5/Qt-5.0.0-r40/lib/libQt5Core.so.5
#52 0x0000000000421ba0 in launcherMain (app=...) at /home/reni/Data/REPOS/webkit_sec/Tools/QtTestBrowser/qttestbrowser.cpp:49
#53 0x0000000000423680 in main (argc=2, argv=0x7fffffffdc58) at /home/reni/Data/REPOS/webkit_sec/Tools/QtTestBrowser/qttestbrowser.cpp:318

[Renata Hodovan]

Created attachment 206971 [details]
Test case

[Rob Buis]

Created attachment 208308 [details]
Patch

[Darin Adler]

Comment on attachment 208308 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=208308&action=review

> Source/WebCore/svg/SVGStyledElement.cpp:334
> +        if (!elementData())
> +            ensureUniqueElementData();

This fix does not look right. The bug seems to be in Element::classAttributeChanged and the fix should be there as well.

[Rob Buis]

Created attachment 208338 [details]
Patch

[Rob Buis]

(In reply to comment #3)
> (From update of attachment 208308 [details])
> View in context: https://bugs.webkit.org/attachment.cgi?id=208308&action=review
> 
> > Source/WebCore/svg/SVGStyledElement.cpp:334
> > +        if (!elementData())
> > +            ensureUniqueElementData();
> 
> This fix does not look right. The bug seems to be in Element::classAttributeChanged and the fix should be there as well.

Right, I just thought that this problem can only happen in SVG, since only in SVG the situation can be that no attributes have been processed and classAttributeChanged is called (through animation). I don't think elementData() can be null when entering classAttributeChanged outside of SVG. I was hesitating between the two approaches a lot... Anyway the new patch tries to fix things in Element::classAttributeChanged.

[Rob Buis]

Committed r153835: <http://trac.webkit.org/changeset/153835>