Create sed to fix CVE-2019-13720 (qtwebengine)

[Douglas R. Reno]

Earlier today, I was made aware of a security vulnerability that is leading to arbitrary code execution via Chromium's audio layer, which affects QtWebEngine (and thus Falkon, which I'll test). The patch looks as if we can add a sed.

Arch Linux Security Advisory ASA-201911-2
=========================================

Severity: Critical
Date    : 2019-11-02
CVE-ID  : CVE-2019-13720
Package : qt5-webengine
Type    : arbitrary code execution
Remote  : Yes
Link    : https://security.archlinux.org/AVG-1059

Summary
=======

The package qt5-webengine before version 5.13.2-2 is vulnerable to
arbitrary code execution.

Resolution
==========

Upgrade to 5.13.2-2.

# pacman -Syu "qt5-webengine>=5.13.2-2"

The problem has been fixed upstream but no release is available yet.

Workaround
==========

None.

Description
===========

A use-after-free vulnerability has been found in the audio component of
the chromium browser before 78.0.3904.87. Google is aware of reports
that an exploit for this vulnerability exists in the wild.

Impact
======

A remote attacker can execute arbitrary code on the affected host.

References
==========

https://bugs.archlinux.org/task/64347
https://code.qt.io/cgit/qt/qtwebengine-chromium.git/patch/?id=d6e5fc10e417efdf8665d9fba57c269f0534072f
https://chromereleases.googleblog.com/2019/10/stable-channel-update-for-desktop_31.html
https://crbug.com/1019226
https://security.archlinux.org/CVE-2019-13720

[Douglas R. Reno]

Please note that this vulnerability is getting a lot of media attention as well

[Douglas R. Reno]

The sed I'm testing:

sed -i '/if (!buffer) {/a \

BaseAudioContext::GraphAutoLocker context_locker(Context()); \n \ MutexLocker locker(process_lock_);' src/3rdparty/chromium/third_party/blink/renderer/modules/webaudio/convolver_node.cc

[Bruce Dubbs]

Doesn't look quite right. Compare with:

sed -e '/!buffer/a \
\    BaseAudioContext::GraphAutoLocker context_locker(Context()); \
\    MutexLocker locker(process_lock_);' \
    -i src/3rdparty/chromium/third_party/blink/renderer/modules/webaudio/convolver_node.cc

[Douglas R. Reno]

Tested Falkon and everything seems to be good. Rendering the book and committing.

[Douglas R. Reno]

Fixed at r22346