Screensaver locks without overlay after resume from suspend

[Thomas Reusch]

Hello,

xfce4-screensaver on my machine is configured to take care of the screen locking when suspended to RAM.

Observed behaviour:
After suspend and resume (lid close, wait for suspent, lid open) I often see the last state of the desktop (frozen) but cannot do anything.
When entering my password "into the blue" (without knowing that there is any input field or anything) and then pressing Enter, the screen is unlocked/unfrozen.

Expected behaviour:
The screen is locked and you cannot see the previous screen content. Either immediately or after moving the mouse or pressing a key, the password prompt is shown.

$ lsb_release -rd
Description: Ubuntu 20.04 LTS
Release: 20.04

$ apt-cache policy xfce4-screensaver
xfce4-screensaver:
  Installiert: 0.1.10-0ubuntu1
  Installationskandidat: 0.1.10-0ubuntu1
  Versionstabelle:
 *** 0.1.10-0ubuntu1 500
        500 http://de.archive.ubuntu.com/ubuntu focal/universe amd64 Packages
        100 /var/lib/dpkg/status

I did "apt update" and "apt dist-upgrade" right before writing this bug report.

If you need more information please let me know.

I marked this as a security bug as it may lead to disclosure of information (desktop content) to others. (Note: It is not a security problem in my case but may be in other constellations)

Kind regards,
Thomas

[Seth Arnold (seth-arnold)]

Thanks for taking the time to report this bug and helping to make Ubuntu better. Since the package referred to in this bug is in universe or multiverse, it is community maintained. If you are able, I suggest coordinating with upstream and posting a debdiff for this issue. When a debdiff is available, members of the security team will review it and publish the package. See the following link for more information: https://wiki.ubuntu.com/SecurityTeam/UpdateProcedures

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[CarbonPepper (carbonpepper)]

This bug probably affects multiple people but is under-reported in one bug because it's hard to identify.

These seem to be the same.
https://bugs.launchpad.net/ubuntu/+source/xfce4-screensaver/+bug/1962818
https://bugs.launchpad.net/ubuntu/+source/xfce4-screensaver/+bug/1881387
https://bugs.launchpad.net/ubuntu/+source/xfce4-screensaver/+bug/1893781