Xfce4: screen visible upon resume before xscreensaver locks it

[Celejar]

Hello,

I'm running Xfce4 on a recent install of Sid. I have configured Xfce4
to "Lock screen before sleep" (in Session and Startup / General), but
when I use xscreensaver, when resuming from suspend the screen is often
visible for a brief period before xscreensaver kicks in. I have not
seen this problem when using light-locker. I also tried briefly with
xfce4-screensaver and did not see the problem, but I have not done
extensive testing with xfce4-screensaver.

This is obviously a serious problem: I see that this has been a
commonly reported Xfce issue, with various distros / screensavers, etc.,
over the years, e.g.:

https://bugs.mageia.org/show_bug.cgi?id=28286
https://bugzilla.xfce.org/show_bug.cgi?id=14782
https://bugzilla.xfce.org/show_bug.cgi?id=15929
https://askubuntu.com/questions/1383379/xubuntu-desktop-visible-after-suspend-before-lock-screen

but I can't make out whether I have misconfigured something here, or
whether this is a serious security bug in the current Xfce4 -
xscreensaver integration.

Celejar

[John Crawley]

On 22/02/2022 23:12, Celejar wrote:
> Hello,
>
> I'm running Xfce4 on a recent install of Sid. I have configured Xfce4
> to "Lock screen before sleep" (in Session and Startup / General), but
> when I use xscreensaver, when resuming from suspend the screen is often
> visible for a brief period before xscreensaver kicks in. I have not
> seen this problem when using light-locker.

>...

> I can't make out whether I have misconfigured something here, or
> whether this is a serious security bug in the current Xfce4 -
> xscreensaver integration.

I can't shed any light on the cause, but can report I see the same thing on a non-xfce system. I'm using lightdm and light-locker, then openbox, although am using some xfce utilities.

Usually when booting up a flash of the previous user desktop is shown before the login window. Agreed, this is not desirable at all. The only possible culprit I can think of is xfdesktop4 - can you try booting to a session with that disabled?

--
John

[John Crawley]

Forgot to mention - I'm not using xscreensaver.

--
John

[Tim Woodall]

I vaguely recall having a similar issue years ago. Managed to find it:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=520633

but now I read through I see it was nothing to do with xscreensaver.

[Celejar]

Thanks for the suggestions - if I manage to do that, I'll report back
with the results.

Celejar