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QCupsPrintEngine::setProperty(): defend against malformed PPK_CupsOptions values

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The QCupsPrintEnginePrivate::closePrintDevice() function expects the
cupsOptions string-list to have an even number of elements, because it
iterates in steps of two and doesn't check the size of the container
while in-between steps.

Print a qWarning() in setProperty() when the option value string-list
has an odd number of elements in it, and append an empty entry to
maintain the expected format for closePrintDevice(). This is the
least-intrusive way to fix the problem, hopefully defining previously
undefined behavior without other user-visible effects.

Amends f70924e9ccc016b979bc74bba156600639184be7, which, however, may
have merely moved the code around.

[ChangeLog][QtPrintSupport][QCupsPrintEngine] Fixed a bug where setting
a value string-list with an odd number of elements as the
PPK_CupsOptions value would read uninitialized data.

Pick-to: 6.5 6.2 5.15
Change-Id: I38ed8de6da00f17fa8fe9138d54db3699943f3b1
Reviewed-by: Ahmad Samir <a.samirh78@gmail.com>
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
(cherry picked from commit 7ae959e00ae4385215ab8bde0781255f36b8bd59)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
This commit is contained in:
Marc Mutz 2024-11-14 14:53:08 +01:00 committed by Qt Cherry-pick Bot
parent 93f32fd47a
commit 1ff68ff3fd
1 changed files with 7 additions and 0 deletions
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7
src/plugins/printsupport/cups/qcupsprintengine.cpp
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@ -64,6 +64,12 @@ void QCupsPrintEngine::setProperty(PrintEnginePropertyKey key, const QVariant &v
break;
case PPK_CupsOptions:
d->cupsOptions = value.toStringList();
if (d->cupsOptions.size() % 2 == 1) {
qWarning("%s: malformed value for key = PPK_CupsOptions "
"(odd number of elements in the string-list; "
"appending an empty entry)", Q_FUNC_INFO);
d->cupsOptions.emplace_back();
}
break;
case PPK_QPageSize:
d->setPageSize(qvariant_cast<QPageSize>(value));
@ -212,6 +218,7 @@ void QCupsPrintEnginePrivate::closePrintDevice()
options.append(QPair<QByteArray, QByteArray>("landscape", ""));
QStringList::const_iterator it = cupsOptions.constBegin();
Q_ASSERT(cupsOptions.size() % 2 == 0);
while (it != cupsOptions.constEnd()) {
options.append(QPair<QByteArray, QByteArray>((*it).toLocal8Bit(), (*(it+1)).toLocal8Bit()));
it += 2;