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QLineF: Don't try calculating a unit vector when length is null

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It's undefined and causes a division by zero.

Fixes: oss-fuzz-24561
Pick-to: 5.12 5.15
Change-Id: Idebaba4b286e3ab0ecb74825d203244958ce6aec
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Robert Loehning 2020-08-03 22:42:23 +02:00
parent e1d7df5ce9
commit c0d0949448
3 changed files with 19 additions and 4 deletions
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1
src/corelib/tools/qline.cpp
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@ -40,7 +40,6 @@
#include "qline.h" #include "qline.h"
#include "qdebug.h" #include "qdebug.h"
#include "qdatastream.h" #include "qdatastream.h"
#include "qmath.h"
#include <private/qnumeric_p.h> #include <private/qnumeric_p.h>
QT_BEGIN_NAMESPACE QT_BEGIN_NAMESPACE

11
src/corelib/tools/qline.h
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@ -40,6 +40,8 @@
#ifndef QLINE_H #ifndef QLINE_H
#define QLINE_H #define QLINE_H
#include "qmath.h"
#include <QtCore/qpoint.h> #include <QtCore/qpoint.h>
QT_BEGIN_NAMESPACE QT_BEGIN_NAMESPACE
@ -369,12 +371,15 @@ constexpr inline QPointF QLineF::center() const
return QPointF(0.5 * pt1.x() + 0.5 * pt2.x(), 0.5 * pt1.y() + 0.5 * pt2.y()); return QPointF(0.5 * pt1.x() + 0.5 * pt2.x(), 0.5 * pt1.y() + 0.5 * pt2.y());
} }
QT_WARNING_DISABLE_FLOAT_COMPARE
inline void QLineF::setLength(qreal len) inline void QLineF::setLength(qreal len)
{ {
if (isNull()) const qreal oldlength = qSqrt(dx() * dx() + dy() * dy());
if (!oldlength)
return; return;
QLineF v = unitVector(); const qreal factor = len / oldlength;
pt2 = QPointF(pt1.x() + v.dx() * len, pt1.y() + v.dy() * len); pt2 = QPointF(pt1.x() + dx() * factor, pt1.y() + dy() * factor);
} }
constexpr inline QPointF QLineF::pointAt(qreal t) const constexpr inline QPointF QLineF::pointAt(qreal t) const

11
tests/auto/corelib/tools/qline/tst_qline.cpp
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@ -40,6 +40,8 @@ private slots:
void testLength(); void testLength();
void testLength_data(); void testLength_data();
void testSetLength();
void testCenter(); void testCenter();
void testCenter_data(); void testCenter_data();
@ -258,6 +260,15 @@ void tst_QLine::testLength()
QCOMPARE(l.dy(), qreal(vy)); QCOMPARE(l.dy(), qreal(vy));
} }
void tst_QLine::testSetLength()
{
QLineF l(0, 0, 4e-323, 5e-324);
const qreal newLength = 1892;
const qreal oldLength = l.length();
l.setLength(newLength);
QCOMPARE(l.length(), oldLength ? newLength : 0);
}
void tst_QLine::testCenter() void tst_QLine::testCenter()
{ {
QFETCH(int, x1); QFETCH(int, x1);