[Bug 249417] New: Desktop visible when screen is locked

[Mohamed Amine IL Idrissi]

https://bugs.kde.org/show_bug.cgi?id=249417

           Summary: Desktop visible when screen is locked
           Product: kde
           Version: unspecified
          Platform: Ubuntu Packages
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: NOR
         Component: general
        AssignedTo: unassigned-bugs at kde.org
        ReportedBy: ilidrissiamine at gmail.com


Version:           unspecified
OS:                Linux

Sometimes when the screen is locked and I press a key to unlock it, I see my
entire desktop and open windows under the password dialog box. That's a
security problem.

I believe this is a compositing / video memory issue, because of the following
factors:

1.) It is intermittent, but occurs most when the screen is "busy" (lots of
graphics-heavy windows open).

2.) I can almost always reproduce it by doing something video-intensive, such
as x11perf.

3.) Sometimes everything will be visible except that one or two windows, or the
"active" portions thereof, will be blacked out.

4.) I have seen other compositing / video memory glitches, such as the contents
of a previously closed window appearing briefly in a newly opened window before
it completes drawing (another security issue in its own right).

5.) The desktop is shown as it appeared when the screen was locked, and does
not update while locked.

6.) I am unable to reproduce the issue with compositing ("desktop effects")
disabled.

Note that the desktop is not dimmed; it is visible for as long as you want to
stare at it, even after the password prompt has disappeared; and I am using
dualhead and both screens are visible, so this is not a duplicate of #390989 or
#385102 or #417722, though it is probably related. I have attached two
screenshots (acquired via VNC) demonstrating the problem.


Reproducible: Didn't try




This bug has been originally reported in Launchpad:
https://bugs.launchpad.net/ubuntu/+source/kdebase-workspace/+bug/474654

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