Bug#910500: libqt5quick5: Sefault in applications using QWebEngineView

[Gabriele Mazzotta <gabriele.mzt@gmail.com>]

Package: libqt5quick5
Version: 5.11.1-6
Severity: important

Hi,

I have a simple Qt application that's been segfaulting ever since
libqt5quick5 has been updated to 5.11.1-6. The crash does not happen
with 5.11.1-5, so I assume the problem is caused by the unaligned
memory access fix that's been backported.

See the following example to reproduce the problem. The crash may
happen while scrolling the page, if not as soon as page is loaded.
Not all the webpages can trigger the bug.

I can provide more info in case the example is not enough to
reproduce the problem.

Regards,
Gabriele

---
$ cat main.cpp
#include <QApplication>
#include <QWebEngineView>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QWebEngineView view;
    view.setUrl(QUrl("https://www.qt.io";));
    view.resize(1024, 750);
    view.show();

    return app.exec();
}

$ cat example.pro
TEMPLATE = app

QT += webenginewidgets

SOURCES += main.cpp

-- System Information:
Debian Release: buster/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.18.0-00081-g078ad232623b (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE= (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages libqt5quick5 depends on:
ii  libc6                                  2.27-6
ii  libqt5core5a [qtbase-abi-5-11-0]       5.11.1+dfsg-9
ii  libqt5gui5                             5.11.1+dfsg-9
ii  libqt5network5                         5.11.1+dfsg-9
ii  libqt5qml5 [qtdeclarative-abi-5-11-0]  5.11.1-6
ii  libstdc++6                             8.2.0-7

libqt5quick5 recommends no packages.

libqt5quick5 suggests no packages.

-- no debconf information