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Fix crash when text contains too many directional chars 

In case a text to be layouted contains more than 128 directional characters
it causes the application to crash

The function initScriptAnalysisAndIsolatePairs() collects information of
RTL/LTR chaaracters into vector "isolatePairs". The size of the vector is
capped to 128. Later the function generateDirectionalRuns() iterates
the text again and tries to access items from the previously capped vector
above the upper bound.

Task-number: QTBUG-77819
Change-Id: Ibb7bf12c12b1db22f43ff46236518da3fdeed26a
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
(cherry picked from commit 1232205e32)
Reviewed-by: Jukka Jokiniva <jukka.jokiniva@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
bb10
Rainer Keller 2019-08-27 14:44:48 +02:00 committed by Jukka Jokiniva
parent 97465b1540
commit af6ac444c9
2 changed files with 24 additions and 8 deletions
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15
src/gui/text/qtextengine.cpp
View File

@ -399,6 +399,7 @@ struct QBidiAlgorithm {
analysis[i].bidiDirection = (level & 1) ? QChar::DirR : QChar::DirL;
runHasContent = true;
lastRunWithContent = -1;
++isolatePairPosition;
}
int runBeforeIsolate = runs.size();
ushort newLevel = isRtl ? ((stack.top().level + 1) | 1) : ((stack.top().level + 2) & ~1);
@ -440,21 +441,19 @@ struct QBidiAlgorithm {
doEmbed(true, true, false);
break;
case QChar::DirLRI:
Q_ASSERT(isolatePairs.at(isolatePairPosition).start == i);
doEmbed(false, false, true);
++isolatePairPosition;
break;
case QChar::DirRLI:
Q_ASSERT(isolatePairs.at(isolatePairPosition).start == i);
doEmbed(true, false, true);
++isolatePairPosition;
break;
case QChar::DirFSI: {
const auto &pair = isolatePairs.at(isolatePairPosition);
Q_ASSERT(pair.start == i);
bool isRtl = QStringView(text + pair.start + 1, pair.end - pair.start - 1).isRightToLeft();
bool isRtl = false;
if (isolatePairPosition < isolatePairs.size()) {
const auto &pair = isolatePairs.at(isolatePairPosition);
Q_ASSERT(pair.start == i);
isRtl = QStringView(text + pair.start + 1, pair.end - pair.start - 1).isRightToLeft();
}
doEmbed(isRtl, false, true);
++isolatePairPosition;
break;
}

17
tests/auto/gui/text/qtextlayout/tst_qtextlayout.cpp
View File

@ -138,6 +138,7 @@ private slots:
void noModificationOfInputString();
void superscriptCrash_qtbug53911();
void showLineAndParagraphSeparatorsCrash();
void tooManyDirectionalCharctersCrash_qtbug77819();
private:
QFont testFont;
@ -2309,5 +2310,21 @@ void tst_QTextLayout::nbspWithFormat()
QCOMPARE(layout.lineAt(1).textLength(), s2.length() + 1 + s3.length());
}
void tst_QTextLayout::tooManyDirectionalCharctersCrash_qtbug77819()
{
QString data;
data += QString::fromUtf8("\xe2\x81\xa8"); // U+2068 FSI character
data += QString::fromUtf8("\xe2\x81\xa7"); // U+2067 RLI character
// duplicating the text
for (int i = 0; i < 10; i++)
data += data;
// Nothing to test. It must not crash in beginLayout().
QTextLayout tl(data);
tl.beginLayout();
tl.endLayout();
}
QTEST_MAIN(tst_QTextLayout)
#include "tst_qtextlayout.moc"