[Bug 1264821] Re: kscreenlock_greet insecure with multiple X screens

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On 2013-12-29T17:30:58+00:00 Kde-1 wrote:

When using multiple X screens (3 in this case), kscreenlocker-greet
behaves very badly and insecurely.

It appears to be drawing the desktop background image/screensaver images
for all three X screens to the primary screen (0) and doesn't
blank/screensave the monitors belonging to screens 1 and 2 (which leaves
their contents in view), and it displays 2, maybe 3 greeter dialogs (1
may be hidden) on the primary X screen, but only accepts typed password
input in 1 of them (the primary X screen's dialog).

Reading the source-code at

ksmserver/screenlocker/greeter/greeterapp.cpp::UnlockApp::desktopResized()

it appears to iterate the screens via desktop()->screenCount() but
assumes there is only one X display when showing the ScreenSaverWindow.


Reproducible: Always

Steps to Reproduce:
1. Configure multiple X screens
2. Lock
Actual Results:  
All background images and screensavers are drawn to X screen 0

Expected Results:  
Each  background image and screensaver should be rendered on the correct X screen

I'm testing a possible fix which passes display()->screen(i) to the
QDeclarativeView constructor.

Photographs of the screens are attached to the referenced Ubuntu bug
report #1264821.

Reply at: https://bugs.launchpad.net/ubuntu/+source/kde-
workspace/+bug/1264821/comments/4

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On 2013-12-31T18:12:34+00:00 Kde-1 wrote:

Created attachment 84383
Render background and greeter on correct X screen

This patch is for version up to 4.11.4.

The re-factoring for Plasma 2 needs a little more research since it
replaces QDeclarativeView with a QQuickView, but the same solution
(passing  QApplication->display()->screen(i)v) looks to be doable if the
QWidget is exchangeable for the QWindow in the QQuickView constructor.

Reply at: https://bugs.launchpad.net/ubuntu/+source/kde-
workspace/+bug/1264821/comments/9


** Changed in: kdebase-workspace
       Status: Unknown => New

** Changed in: kdebase-workspace
   Importance: Unknown => High

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Title:
  kscreenlock_greet insecure with multiple X screens

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