Bug 223144 – [ macOS debug arm64 ] ASSERTION FAILED: count >= 1 ./rendering/RenderMultiColumnSet.cpp(450) : unsigned int WebCore::RenderMultiColumnSet::columnCount() const

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[Robert Jenner]

fast/multicol/crash-when-spanner-candidate-is-out-of-flow.html

is crashing/an Assertion Failure in macOS Debug on Apple Silicon only.

HISTORY URL:
https://results.webkit.org/?suite=layout-tests&test=fast%2Fmulticol%2Fcrash-when-spanner-candidate-is-out-of-flow.html

CRASHLOG TEXT:
ASSERTION FAILED: count >= 1
./rendering/RenderMultiColumnSet.cpp(450) : unsigned int WebCore::RenderMultiColumnSet::columnCount() const
1   0x135b34bcc WTFCrash
2   0x114ae0da0 WebCore::JSRTCRtpReceiver::createPrototype(JSC::VM&, WebCore::JSDOMGlobalObject&)
3   0x1183b1a3c WebCore::RenderMultiColumnSet::columnCount() const
4   0x1183b3ff8 WebCore::RenderMultiColumnSet::addOverflowFromChildren()
5   0x1181b12e4 WebCore::RenderBlock::computeOverflow(WebCore::LayoutUnit, bool)
6   0x1181d2038 WebCore::RenderBlockFlow::computeOverflow(WebCore::LayoutUnit, bool)
7   0x1181c796c WebCore::RenderBlockFlow::layoutBlock(bool, WebCore::LayoutUnit)
8   0x1181b0dfc WebCore::RenderBlock::layout()
9   0x1183b2254 WebCore::RenderMultiColumnSet::layout()
10  0x1181c98b8 WebCore::RenderBlockFlow::layoutBlockChild(WebCore::RenderBox&, WebCore::RenderBlockFlow::MarginInfo&, WebCore::LayoutUnit&, WebCore::LayoutUnit&)
11  0x1181c82f8 WebCore::RenderBlockFlow::layoutBlockChildren(bool, WebCore::LayoutUnit&)
12  0x1181c7588 WebCore::RenderBlockFlow::layoutBlock(bool, WebCore::LayoutUnit)
13  0x1181c8490 WebCore::RenderBlockFlow::relayoutForPagination()
14  0x1181c767c WebCore::RenderBlockFlow::layoutBlock(bool, WebCore::LayoutUnit)
15  0x1181b0dfc WebCore::RenderBlock::layout()
16  0x1180fbfdc WebCore::RenderElement::layoutIfNeeded()
17  0x1181b37bc WebCore::RenderBlock::layoutPositionedObject(WebCore::RenderBox&, bool, bool)
18  0x1181b304c WebCore::RenderBlock::layoutPositionedObjects(bool, bool)
19  0x1181c7938 WebCore::RenderBlockFlow::layoutBlock(bool, WebCore::LayoutUnit)
20  0x1181b0dfc WebCore::RenderBlock::layout()
21  0x11846b094 WebCore::RenderView::layout()
22  0x11781e0e0 WebCore::FrameViewLayoutContext::layout()
23  0x1168c68ac WebCore::Document::implicitClose()
24  0x1175ddadc WebCore::FrameLoader::checkCallImplicitClose()
25  0x1175dd5b4 WebCore::FrameLoader::checkCompleted()
26  0x1175db7dc WebCore::FrameLoader::finishedParsing()
27  0x1168d9b10 WebCore::Document::finishedParsing()
28  0x1170fa1dc WebCore::HTMLConstructionSite::finishedParsing()
29  0x117141d5c WebCore::HTMLTreeBuilder::finished()
30  0x117101644 WebCore::HTMLDocumentParser::end()
31  0x1170ff4fc WebCore::HTMLDocumentParser::attemptToRunDeferredScriptsAndEnd()
LEAK: 1 WebPageProxy

[Radar WebKit Bug Importer]

<rdar://problem/75381496>

[Robert Jenner]

Created attachment 423089 [details]
223144-Full Crashlog

Attaching the full Crashlog to this bug.

[Robert Jenner]

I cannot reproduce the crash as it is only occurring on an Apple Silicon Mac, and I do not have access to one. It should also be noted that this has been crashing since it started running on an Apple Silicon Mac.

[Alexey Proskuryakov]

This stack trace looks hilariously wrong. I really hope that it is wrong.

This does reproduce locally as is.

[Alexey Proskuryakov]

When reproducing locally, the stack trace looked normal.

[Robert Jenner]

Updating test expectations to Crash while test is being reviewed: 

https://trac.webkit.org/changeset/274515/webkit

[Chris Dumez]

The issue is that static_cast<float>(logicalHeightInColumns) is negative (-1.67771e+07). With ceil(), we end up with -108941.0 which we try to implicitly cast to an unsigned variable.

Converting a negative double into an unsigned integer type is undefined behavior. I am guessing the real issue though is that logicalHeightInColumns should likely not be negative..

[Chris Dumez]

Created attachment 423666 [details]
Patch

[Chris Dumez]

I am trying to find out how we end up with a negative value in the first place

[Chris Dumez]

(In reply to Chris Dumez from comment #9)
> I am trying to find out how we end up with a negative value in the first
> place

RenderFragmentContainer::setFragmentedFlowPortionRect(-1.67771e+07, 300)
1   0x26ce2c9be WebCore::RenderFragmentContainer::setFragmentedFlowPortionRect(WebCore::LayoutRect const&)
2   0x26ce2f152 WebCore::RenderFragmentContainerSet::expandToEncompassFragmentedFlowContentsIfNeeded()
3   0x26cf37910 WebCore::RenderMultiColumnFlow::layout()
4   0x26cd720c9 WebCore::RenderBlockFlow::layoutExcludedChildren(bool)
5   0x26cd5f827 WebCore::RenderBlockFlow::layoutBlockChildren(bool, WebCore::LayoutUnit&)
6   0x26cd5e7e3 WebCore::RenderBlockFlow::layoutBlock(bool, WebCore::LayoutUnit)
7   0x26cd5fadc WebCore::RenderBlockFlow::relayoutForPagination()
8   0x26cd5e918 WebCore::RenderBlockFlow::layoutBlock(bool, WebCore::LayoutUnit)
9   0x26cd45f69 WebCore::RenderBlock::layout()
10  0x26cc9dcdc WebCore::RenderElement::layoutIfNeeded()
11  0x26cd48a37 WebCore::RenderBlock::layoutPositionedObject(WebCore::RenderBox&, bool, bool)
12  0x26cd482fe WebCore::RenderBlock::layoutPositionedObjects(bool, bool)
13  0x26cd5ed5a WebCore::RenderBlockFlow::layoutBlock(bool, WebCore::LayoutUnit)
14  0x26cd45f69 WebCore::RenderBlock::layout()
15  0x26cfe4f13 WebCore::RenderView::layout()
16  0x26c4cf811 WebCore::FrameViewLayoutContext::layout()
17  0x26b70d666 WebCore::Document::implicitClose()
18  0x26c2c7b7b WebCore::FrameLoader::checkCallImplicitClose()
19  0x26c2c75aa WebCore::FrameLoader::checkCompleted()
20  0x26c2c5697 WebCore::FrameLoader::finishedParsing()
21  0x26b722176 WebCore::Document::finishedParsing()
22  0x26be5ccc8 WebCore::HTMLConstructionSite::finishedParsing()
23  0x26bea2a07 WebCore::HTMLTreeBuilder::finished()
24  0x26be642f8 WebCore::HTMLDocumentParser::end()
25  0x26be61fc8 WebCore::HTMLDocumentParser::attemptToRunDeferredScriptsAndEnd()
26  0x26be61d07 WebCore::HTMLDocumentParser::prepareToStopParsing()
27  0x26be64362 WebCore::HTMLDocumentParser::attemptToEnd()
28  0x26be64429 WebCore::HTMLDocumentParser::finish()
29  0x26c29fba4 WebCore::DocumentWriter::end()
30  0x26c251f44 WebCore::DocumentLoader::finishedLoading()
31  0x26c2518e1 WebCore::DocumentLoader::notifyFinished(WebCore::CachedResource&, WebCore::NetworkLoadMetrics const&)

[Chris Dumez]

(In reply to Chris Dumez from comment #10)
> (In reply to Chris Dumez from comment #9)
> > I am trying to find out how we end up with a negative value in the first
> > place
> 
> RenderFragmentContainer::setFragmentedFlowPortionRect(-1.67771e+07, 300)
> 1   0x26ce2c9be
> WebCore::RenderFragmentContainer::setFragmentedFlowPortionRect(WebCore::
> LayoutRect const&)
> 2   0x26ce2f152
> WebCore::RenderFragmentContainerSet::
> expandToEncompassFragmentedFlowContentsIfNeeded()
> 3   0x26cf37910 WebCore::RenderMultiColumnFlow::layout()
> 4   0x26cd720c9 WebCore::RenderBlockFlow::layoutExcludedChildren(bool)
> 5   0x26cd5f827 WebCore::RenderBlockFlow::layoutBlockChildren(bool,
> WebCore::LayoutUnit&)
> 6   0x26cd5e7e3 WebCore::RenderBlockFlow::layoutBlock(bool,
> WebCore::LayoutUnit)
> 7   0x26cd5fadc WebCore::RenderBlockFlow::relayoutForPagination()
> 8   0x26cd5e918 WebCore::RenderBlockFlow::layoutBlock(bool,
> WebCore::LayoutUnit)
> 9   0x26cd45f69 WebCore::RenderBlock::layout()
> 10  0x26cc9dcdc WebCore::RenderElement::layoutIfNeeded()
> 11  0x26cd48a37
> WebCore::RenderBlock::layoutPositionedObject(WebCore::RenderBox&, bool, bool)
> 12  0x26cd482fe WebCore::RenderBlock::layoutPositionedObjects(bool, bool)
> 13  0x26cd5ed5a WebCore::RenderBlockFlow::layoutBlock(bool,
> WebCore::LayoutUnit)
> 14  0x26cd45f69 WebCore::RenderBlock::layout()
> 15  0x26cfe4f13 WebCore::RenderView::layout()
> 16  0x26c4cf811 WebCore::FrameViewLayoutContext::layout()
> 17  0x26b70d666 WebCore::Document::implicitClose()
> 18  0x26c2c7b7b WebCore::FrameLoader::checkCallImplicitClose()
> 19  0x26c2c75aa WebCore::FrameLoader::checkCompleted()
> 20  0x26c2c5697 WebCore::FrameLoader::finishedParsing()
> 21  0x26b722176 WebCore::Document::finishedParsing()
> 22  0x26be5ccc8 WebCore::HTMLConstructionSite::finishedParsing()
> 23  0x26bea2a07 WebCore::HTMLTreeBuilder::finished()
> 24  0x26be642f8 WebCore::HTMLDocumentParser::end()
> 25  0x26be61fc8
> WebCore::HTMLDocumentParser::attemptToRunDeferredScriptsAndEnd()
> 26  0x26be61d07 WebCore::HTMLDocumentParser::prepareToStopParsing()
> 27  0x26be64362 WebCore::HTMLDocumentParser::attemptToEnd()
> 28  0x26be64429 WebCore::HTMLDocumentParser::finish()
> 29  0x26c29fba4 WebCore::DocumentWriter::end()
> 30  0x26c251f44 WebCore::DocumentLoader::finishedLoading()
> 31  0x26c2518e1
> WebCore::DocumentLoader::notifyFinished(WebCore::CachedResource&,
> WebCore::NetworkLoadMetrics const&)

In RenderFragmentContainerSet::expandToEncompassFragmentedFlowContentsIfNeeded():
```
LayoutUnit logicalHeightWithOverflow = (isHorizontal ? layoutRect.maxY() : layoutRect.maxX()) - logicalTopOffset;
```

isHorizontal is true, layoutRect.maxY() is 154 and logicalTopOffset is 1.67772e+07.
As a result, `layoutRect.maxY() - logicalTopOffset` becomes negative.

[Chris Dumez]

Zalan will be taking over to figure out why we end up with a negative value in RenderFragmentContainerSet::expandToEncompassFragmentedFlowContentsIfNeeded() and a proper fix.

[alan]

Created attachment 423754 [details]
Patch

[alan]

Created attachment 423803 [details]
Patch

[EWS]

Committed r274774: <https://commits.webkit.org/r274774>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 423803 [details].