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[Bug 1396205] Re: Lock screen can be bypassed using a large monitor

 

** Information type changed from Private Security to Public Security

** Package changed: unity (Ubuntu) => gnome-screensaver (Ubuntu)

** Changed in: gnome-screensaver (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1396205

Title:
  Lock screen can be bypassed using a large monitor

Status in “gnome-screensaver” package in Ubuntu:
  Confirmed

Bug description:
  $ lsb_release -rd
  Description:	Ubuntu 12.04.5 LTS
  Release:	12.04

  I've managed to reproduce an error that lets me interact with
  applications while the lock screen is active. Here are the steps to
  reproduce, as specifically as I've been able to tell:

  1. I have my Dell XPS laptop attached to a Benq desktop monitor via
  the laptop's mini DVI port. The laptop is closed, the screen is
  unlocked, and the desktop monitor shows my Ubuntu desktop and apps.

  2. Unplug the display cable from the laptop and open the laptop up.
  Wait a couple of seconds for the monitor to report no input device.
  The screen should still be unlocked and the laptop screen should show
  the OS desktop.

  3. Plug the display cable back in, and immediately close the laptop.

  4. Observe that moving the mouse (Evoluent vertical mouse attached to
  an Apple keyboard, plugged into the laptop via USB) does not bring up
  the login dialog. The desktop monitor remains blank.

  5. Open the laptop lid slightly, and as soon as the screen blacks out,
  close it again. The desktop monitor should remain blank.

  6. Move the mouse. This time, the lock screen login dialog appears on
  the desktop monitor, but it does not cover the whole desktop. I am
  able to interact with a web browser running behind the lock screen,
  read pages, click links, etc.

  It seems like the lock screen is drawn for my laptop's small screen,
  and then not enlarged for the bigger monitor, leaving apps visible and
  accepting mouse input.

  See the attached image for an example. I can repro this bug every time
  by following the above instructions.

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: unity 5.20.0-0ubuntu3
  ProcVersionSignature: Ubuntu 3.13.0-40.69~precise1-generic 3.13.11.10
  Uname: Linux 3.13.0-40-generic x86_64
  ApportVersion: 2.0.1-0ubuntu17.8
  Architecture: amd64
  CompizPlugins: [core,composite,opengl,compiztoolbox,decor,vpswitch,move,snap,place,session,gnomecompat,mousepoll,regex,resize,imgpng,grid,unitymtgrabhandles,animation,workarounds,wall,fade,scale,expo,ezoom,unityshell]
  Date: Tue Nov 25 14:53:21 2014
  EcryptfsInUse: Yes
  InstallationMedia: Ubuntu 12.04.3 LTS "Precise Pangolin" - Release amd64 (20130820.1)
  MarkForUpload: True
  ProcEnviron:
   LANGUAGE=en_GB:en
   TERM=xterm-256color
   PATH=(custom, no user)
   LANG=en_GB.UTF-8
   SHELL=/bin/bash
  SourcePackage: unity
  UpgradeStatus: No upgrade log present (probably fresh install)

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