Ubuntu
xfce4-screensaver package

Cannot enter password to unlock session

Bug #1875025 reported by Jakub Vaněk
172
This bug affects 38 people
Affects Status Importance Assigned to Milestone
Xfce Screensaver
New
Unknown
xfce4-screensaver (Ubuntu)
Confirmed
Undecided
Unassigned

Bug Description

When a timer triggers xfce4-screensaver and it locks the screen, it is impossible to unlock it. I can log into LightDM but then I get stuck on the locker's login screen. I would like to enter my password, but I cannot - the password field is not editable, only its hint text can be selected.

The system is a recent upgrade from Xubuntu 18.04.4 to Xubuntu 20.04.
---
ProblemType: Bug
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: XFCE
DistroRelease: Ubuntu 20.04
NonfreeKernelModules: talpa_vfshook talpa_pedconnector talpa_pedevice talpa_vcdevice talpa_core talpa_linux talpa_syscallhook
Package: xfce4-screensaver 0.1.10-0ubuntu1
PackageArchitecture: amd64
ProcVersionSignature: Ubuntu 5.4.0-26.30-generic 5.4.30
Tags: focal
Uname: Linux 5.4.0-26-generic x86_64
UpgradeStatus: Upgraded to focal on 2020-04-24 (0 days ago)
UserGroups: adm cdrom dip docker lpadmin pkcs11 plugdev sambashare sudo tss
_MarkForUpload: True

See original description
Revision history for this message
In , Kevin-grigorenko (kevin-grigorenko) wrote :

After setting the screensaver lock timeout to 10 minutes, waiting 10 minutes, and then activating the screen, the password entry does not allow text input and the user is locked out.

Demonstration: https://www.youtube.com/watch?v=tUqdmKIucbM

To reproduce, use this Docker image: https://hub.docker.com/r/kgibm/fedorawasdebug

1. Note: You'll need more than 20GB of disk space and configure Docker with 4GB or more of RAM. For detailed instructions, see the Lab PDF at https://raw.githubusercontent.com/kgibm/dockerdebug/master/fedorawasdebug/WebSphere_Application_Server_Troubleshooting_and_Performance_Lab_on_Docker.pdf
2. docker run --cap-add SYS_PTRACE --ulimit core=-1 --ulimit memlock=-1 --ulimit stack=-1 --shm-size="256m" --rm -p 9080:9080 -p 9443:9443 -p 9043:9043 -p 9081:9081 -p 9444:9444 -p 5901:5901 -p 5902:5902 -p 3390:3389 -p 22:22 -p 9082:9082 -p 9083:9083 -p 9445:9445 -p 8080:8080 -p 8081:8081 -p 8082:8082 -p 12000:12000 -p 12005:12005 -it kgibm/fedorawasdebug
3. The container is fully started after about 2 minutes when the output shows: = READY =
4. Remote into the docker image with password 'websphere' (no quotes). Linux: vncviewer localhost:5902. Mac: open vnc://localhost:5902. Windows: Remote desktop (see lab instructions), or use a free VNC client.
5. Open Settings > Screensaver and change the timeout to 10 minutes
6. Idle for 10 minutes
7. Activate the screen
8. Try to type in the password 'websphere' (no quotes) but typing does not work.
9. User is locked out.

The image is built using the following three layers of Dockerfiles (instructions on how to build each Dockerfile are in comments at the top of the Dockerfile):

1. Fedora image: https://github.com/kgibm/dockerdebug/blob/master/fedoradebug/Dockerfile
2. Java image: https://github.com/kgibm/dockerdebug/blob/master/fedorajavadebug/Dockerfile
3. Final image: https://github.com/kgibm/dockerdebug/blob/master/fedorawasdebug/Dockerfile

For those unfamiliar with Docker, if you want to debug the issue after it occurs, you may "login" to the running container using:

docker ps

Take the container ID and then:

docker exec -it $containerid bash

Revision history for this message
In , Kevin-grigorenko (kevin-grigorenko) wrote :

Key events in the YouTube video:

1. 0:07 - First starting with a 1 minute idle timeout: https://youtu.be/tUqdmKIucbM?t=7
2. 1:24 - Activating the screen after a minute works: https://youtu.be/tUqdmKIucbM?t=84
3. 1:36 - Change to 5 minute idle timeout: https://youtu.be/tUqdmKIucbM?t=96
4. 6:56 - Activating the screen after 5 minutes works: https://youtu.be/tUqdmKIucbM?t=416
5. 7:08 - Change to 10 minute idle timeout: https://youtu.be/tUqdmKIucbM?t=428
6. 17:23 - Activating the screen after 10 minutes does not work: https://youtu.be/tUqdmKIucbM?t=1043

Revision history for this message
In , Kevin-grigorenko (kevin-grigorenko) wrote :

This is caused by xscreensaver locking at 10 minutes (as seen by `xset q`). Worked around the problem with the following (not installing xscreensaver* didn't help as something seems to bring it in as a dependency):

rm -rf /etc/xdg/autostart/xscreensaver*

Revision history for this message
In , Kevin-grigorenko (kevin-grigorenko) wrote :

Note that the reproduction noted above will no longer work as I pushed a new version of the image into DockerHub with the fix in comment 2; however, the problem should be easily reproducible by simply installing both xscreensaver and xfce4-screensaver.

Revision history for this message
In , Alexander Butenko (avb) wrote :

im not sure what to with this problem. The only possible workaround here is not to start xfce4-screensaver daemon if xscreensaver is detected.
what is the point of having both xscreensaver and xfce4-screensaver running?

Revision history for this message
In , Kevin-grigorenko (kevin-grigorenko) wrote :

(In reply to Alexander Butenko from comment #4)
> im not sure what to with this problem. The only possible workaround here is
> not to start xfce4-screensaver daemon if xscreensaver is detected.
> what is the point of having both xscreensaver and xfce4-screensaver running?

Not installing xscreensaver* didn't help as something seems to bring it in as a dependency. I had to explicitly do $(rm -rf /etc/xdg/autostart/xscreensaver*). I think it would be nice if xfce4-screensaver protected itself from this situation because it was very hard to figure out and of course a completely locked screen is pretty scary.

Revision history for this message
Jakub Vaněk (vanek-jakub4) wrote :

The bug may be related to https://bugzilla.xfce.org/show_bug.cgi?id=16140. However, it seems that they have resolved it by removing xscreensaver and I don't have xscreensaver installed. On the other hand, I have light-locker installed - this may be causing a similar conflict.

no longer affects: xfce4-screensaver
Revision history for this message
Jakub Vaněk (vanek-jakub4) wrote :

Indeed, reinstalling xfce4-screensaver and removing light-locker solves the issue as well.

Revision history for this message
In , Jakub Vaněk (linuxtardis) wrote :

It seems that similar bug can be triggered when light-locker is running in parallel with xfce4-screensaver, see https://bugs.launchpad.net/xfce4-screensaver/+bug/1875025. I'm afraid that this will cause problems for people upgrading from Xubuntu 18.04, where light-locker was installed by default AFAIK.

Revision history for this message
In , Jakub Vaněk (linuxtardis) wrote :

(In reply to Alexander Butenko from comment #4)
> im not sure what to with this problem. The only possible workaround here is
> not to start xfce4-screensaver daemon if xscreensaver is detected.
> what is the point of having both xscreensaver and xfce4-screensaver running?

I think that is OK, although it would make xfce4-screensaver susceptible to being disabled by creating a dummy xscreensaver/light-locker process. On the other hand, it can be killed by any user process anyway.

Disclaimer: I don't know xfce or screensaver internals.

Revision history for this message
Jakub Vaněk (vanek-jakub4) wrote : Dependencies.txt

apport information

tags: added: apport-collected focal
description: updated
Revision history for this message
Jakub Vaněk (vanek-jakub4) wrote : ProcCpuinfoMinimal.txt

apport information

Revision history for this message
Jakub Vaněk (vanek-jakub4) wrote : ProcEnviron.txt

apport information

Bug Watch Updater (bug-watch-updater)
Changed in xfce4-screensaver:
importance: Unknown → High
status: Unknown → Confirmed
Revision history for this message
Launchpad Janitor (janitor) wrote :

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

Changed in xfce4-screensaver (Ubuntu):
status: New → Confirmed
Revision history for this message
Stefan Fleischmann (sfleischmann) wrote :

The file /etc/xdg/autostart/xscreensaver.desktop belongs to the xfce4-session package, see
/var/lib/dpkg/info/xfce4-session.conffiles

On a fresh Xubuntu 20.04 installation the light-locker package is not installed, that would explain why not more people are affected by this.

Revision history for this message
Jakub Vaněk (vanek-jakub4) wrote :

That's interesting, thank you for your reply. I think that adding the light-locker package to the Conflicts: field of xfce4-session package in Ubuntu 20.04 would fix this. On the other hand, it seems a bit too strict - one may want to use light-locker instead of xscreensaver and this would make that impossible AFAIK. Alternatively the upgrade script could be improved so that the light-locker package gets removed during the upgrade.

Revision history for this message
Daniel Lange (dlange) wrote :

In either case please fix this before many people do LTS upgrades (20.04.1).

The double lock where no password can be typed in is nasty.

Revision history for this message
Ravin Kumar (canyon289) wrote :

Adding confirmation that this is affecting me as well. Commenting to get updates

Revision history for this message
Ravin Kumar (canyon289) wrote :

Apologies I didn't realize I can't edit my post. I upgraded from 18.04 and just hit confirm on every prompt during the upgrade. This was not a clean install to 20.04 directly

Revision history for this message
Pancho Pico (panchopico) wrote :

Adding confirmation that this is affecting me as well. Commenting to get updates and to report that uninstalling light-locker seems to have worked for me. I also updated to 20.04 from 18.04.

Revision history for this message
Greyson (grbdevnull) wrote :

Please note that this issue can also occur on a direct install of Xubuntu 20.04 if the user installs another desktop environment that includes xscreensaver. I installed several other desktop environments, so I am not sure which one added xscreensaver, but I am now experiencing this issue as a result despite using a fresh install of Xubuntu 20.04 on my test machine.

Jarno Suni (jarnos)
Changed in xfce4-screensaver:
importance: High → Unknown
status: Confirmed → Unknown
Revision history for this message
Ari Sovijärvi (apz-fi) wrote :

Observed this one 2 separate cases, one Xubuntu 18.04 -> 20.04 installation where light-locker caused it and on a fresh Lubuntu 20.04, that was converted to XFCE, where xscreensaver was the issue. Also had 3 other Xubuntu installations that went from 18.04 to 20.04 and did not encounter these issues.

Revision history for this message
Craig Harding (craigwharding) wrote :

I upgraded from Xubuntu 16.04->18.04 and then 18.04->20.04.1
I get this same behavior when laptop lid is closed and re-opened for new session. I've temporarily disabled 'Enable Lock Screen' under the Screensaver Preferences screen as a work around for now. See attached snippet from my journal log (removing irrelevant entries)..

I do not have xscreensaver installed but light-locker binary is present.

Revision history for this message
Aaditya Bagga (chk1827) wrote :

Same issue here.

I am guessing xfce4-screensaver should conflict with and remove light-locker when its installed as suggested in a comment above.

Updated from Ubuntu + Xfce (xubuntu-desktop) 18.04 -> 20.04.1. Used work around like Craig above, and disabled lock part in xfce4-screensaver.

Revision history for this message
Qianqian Fang (fangq) wrote :

I recently added two Ubuntu 20.04 servers to my existing Ubuntu machines in the lab, and started experiencing something similar to this reported bug.

the problem happens when I remotely connect my new servers using x2go, and leave the session idle over >5 min. The x2go remote desktop screen appears to be frozen, no screensaver or password prompt is shown. The cursor is shown as an I-beam shape. However if I resize the x2go window, the desktop resizes accordingly. The only way for me to reactivate this remote window is to ssh to the server and kill the xfce4-screensaver process "/usr/bin/xfce4-screensaver --no-daemon"

My xfce4 screensaver is set as a blank screen, locking the screen after 5 min idle.

Please let me know if there is a workaround for this. I do not want to disable screensaver because it also disables this setting on my other machines because they share the same home dir via nfs.

Revision history for this message
rasos (rasos) wrote :

Upgraded from Xubuntu 18.04 to 20.04. Could not type in password after resume or lock. Fixed it with:

sudo apt remove light-locker

Revision history for this message
Knox Hamilton (l1knox) wrote :

Confirmed. Upgraded from 18.04 to 20.04.1. Walked away from my computer, came back and couldn't log in: Unlock, presented with another password prompt that could not accept input.

Have purged light-locker, will see how that fares.

So bad that I created a "Ubuntu One" account just to provide feedback (unrelated: fix that damned crash reporter already, it's garbage... should not have to sudo rm /var/crash/*)

Revision history for this message
Martin (martin-aumont) wrote :

I finally got the upgrade prompt yesterday. I wanted a stable 18.04 -> 20.04 upgrade so I waited for it to be officially ready. All seemed flawless except after suspending I couldn't log back in.

Removing light-locker and reinstalling xfce4-screensaver did fix it. Thanks to previous posters for the suggestions.

Now that users are getting prompted to upgrade I suspect a lot more people will be bitten by this.

Revision history for this message
R. Diez (rdiezmail-ubuntu) wrote :

This bug is actually many years old:

https://bugs.launchpad.net/ubuntu/+source/xubuntu-default-settings/+bug/1304128

Revision history for this message
Barbora Lepková (b.lepkova) wrote :

Hello, I am adding my experience. The same problem, it was temporarily solved by disabling screensaver but now I must turn my laptop off every single time. Fresh install of Xubuntu 20.

Revision history for this message
Hasenkopf, Andreas (andi-hasenkopf) wrote :

Hi, I have upgraded two machines from Xubuntu 18.04 to 20.04 using the ’do_release_upgrade’ command.

The strange thing is, I have the same problem on the laptop (fresh install of 18.04), but not on the desktop machine (upgraded from 16.04 to 18.04).

Not sure, if this insight provides any help...

Revision history for this message
abssorb (abssorb) wrote :

Also occurs if you make a fresh install of Ubuntu 20.04.2, and then add xubuntu-desktop

light-locker remains in place and needs to be removed manually.

Revision history for this message
Mikhail Yevchenko (mikhail-yevchenko) wrote :

I have a lubuntu with xfce4 installed. And it's worse. It doesn't accept passwords. But you can just click "new login" and get logged in without any password.

Revision history for this message
Jiuke Chen (joyalwaysbejoyful) wrote :

FYI, I have Ubuntu 20.04 installed and everything was going well with xrdp. Then I installed xubuntu. When I log in with xfce session, I cannot type the password remotely. But now is good. For me, removal of light-locker and disable screensaver are solutions.

Revision history for this message
Douglas King (douglask) wrote :

Similar situation. Upgraded to xubutnu 20.04 LTS. My primary use of this system is ssh and RDP as I'm rarely in the same room. There is a monitor attached, so removing light-locker is insecure.

Revision history for this message
joshyg6 (josheg) wrote :

Can one remove or disable xscreensaver, but leave xfce4-screensaver? What are the consequences doing so? What are the steps to do so?

Revision history for this message
Jarno Suni (jarnos) wrote :

Please ask in askubuntu.com.

Bug Watch Updater (bug-watch-updater)
Changed in xfce4-screensaver:
status: Unknown → New
Revision history for this message
Muhammad Atif Ali (matifali) wrote :

I am using Xubuntu-22.04 and logged in through xrdp and have been locked out from my account. I can not enter my password.
I have removed light-docker and screensaver
and I have done reinstall xfce4-screensaver

Revision history for this message
Namhyeon Go (gnh1201) wrote :

I can not enter my password, too. I am using xfce4 on Ubuntu 22.04. It looks like the "readonly" textbox.

Revision history for this message
Andreas L (avl42) wrote :

One more "me, too"...

I installed Ubuntu 22.04 fresh and then did "apt install xfce4"

screenlock(dialog looks xfce'ish) now cannot be unlocked, password field doesn't get focus.

It seems to me bizarre to have to uninstall light-locker or xscreensaver, because these packages might be needed for other desktops (different users on a machine might prefer different desktops!).

There must be a way from the xfce session to just *not-start* any conflicting screensavers...

Revision history for this message
Andreas L (avl42) wrote :

One more update... (after playing some more with xfce)

Normally I lock the screen manually using the keyboard-shortcut (which results in the screen being locked by the xfce lock.)

If instead I switch user, then the "xscreensaver" kicks in instead of the xfce lock.

Returning to my own user lateron then means that I enter password on the dm, then again into xscreensaver's dialog.

The problematic case seems to be, when I manually start the xfce-lock (e.g. using the keycombo), and lateron the xscreensaver activates itself based on idle-time.

While the xfce lock is active, it just ought to *suppress* the xscreensaver (or light-locker, whatever) and the problem should be solved.

Revision history for this message
Jarno Suni (jarnos) wrote :

@avl42 see the related upstream issues: https://gitlab.xfce.org/xfce/xfce4-session/-/issues/68
and https://gitlab.xfce.org/xfce/xfce4-session/-/issues/149

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