Gnome session fails to lock automatically when VirtualBox VM is in the foreground

[Alex Jones]

In Ubuntu Gnome 16.04, if a VirtualBox VM is in the foreground, Gnome will not lock the screen automatically, and will display a message that it couldn't lock the screen. This could allow an unauthorized user with physical access to gain access to the session. Locking the session manually from the menu still works.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: gnome-shell 3.18.5-0ubuntu0.3
ProcVersionSignature: Ubuntu 4.10.0-33.37~16.04.1-generic 4.10.17
Uname: Linux 4.10.0-33-generic x86_64
NonfreeKernelModules: nvidia_uvm zfs zunicode zavl zcommon znvpair nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.1-0ubuntu2.10
Architecture: amd64
CurrentDesktop: GNOME
Date: Tue Sep 12 18:58:03 2017
DisplayManager: gdm3
GsettingsChanges:
 b'org.gnome.shell' b'favorite-apps' b"['google-chrome.desktop', 'evolution.desktop', 'empathy.desktop', 'rhythmbox.desktop', 'org.gnome.Photos.desktop', 'libreoffice-writer.desktop', 'org.gnome.Nautilus.desktop', 'yelp.desktop']"
 b'org.gnome.desktop.interface' b'gtk-im-module' b"'gtk-im-context-simple'"
 b'org.gnome.desktop.interface' b'clock-format' b"'12h'"
JournalErrors:
 Error: command ['journalctl', '-b', '--priority=warning', '--lines=1000'] failed with exit code 1: Hint: You are currently not seeing messages from other users and the system.
       Users in the 'systemd-journal' group can see all messages. Pass -q to
       turn off this notice.
 No journal files were opened due to insufficient permissions.
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-shell
UpgradeStatus: No upgrade log present (probably fresh install)

[Seth Arnold (seth-arnold)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 49579, so it is being marked as such.

This is a fundamental bug in the design of X11 and cannot be easily fixed within X11.

You should manually lock your screen if a locked session is important to you.

Please continue to report any other bugs you may find.