Disabled animations breaks lock screen and other dialogs, reveals information from the screen without unlocking

[Andrew Kornilov]

Dear Ubuntu Team,
I'm using the latest Ubuntu 20 focal, update it every day.
After some of the upgrades something happened and screenlock and other dialogs became broken (i'll describe below).
It was very hard to find what caused this (i reset all keys in dconf one by one and restarted) and finally i found it: /org/gnome/desktop/interface/enable-animations My animations were disabled (they are slow even on supertop hardware).

So the problem is: it seems that new GNOME 3.36 lock screen and other dialogs like "Ask for a root password" rely on animations and without it they do not work or work incorrectly/insecure.

1. Screenlock can lock a screen without any problem. When i try to unlock it and click by mouse/key, i except a dialog with password prompt to appear. However, instead of the dialog Screenlock just shows my screen and running applications with all my data, for some time. Then it again locks the screen. I can repeat this as many times as i want and steal all the information. See the attached video, you will see the dconf-editor running. Sorry for the video quality.

The only way to unlock the screen is to click an icon at the bottom-right "Change user". Then i get a list of users, can choose myself and type a password.

2. Other dialogs like asking for a root password (when it's required to run an application under root), just do not appear. Screen blinks and that's all.

Thank you.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gnome-shell 3.35.91-1ubuntu2
ProcVersionSignature: Ubuntu 5.4.0-17.21-generic 5.4.22
Uname: Linux 5.4.0-17-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu18
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Thu Mar 5 23:32:51 2020
DisplayManager: gdm3
InstallationDate: Installed on 2019-12-11 (85 days ago)
InstallationMedia: Ubuntu-Server 19.10 "Eoan Ermine" - Release amd64 (20191017)
RelatedPackageVersions: mutter-common 3.35.91-1ubuntu1
SourcePackage: gnome-shell
UpgradeStatus: No upgrade log present (probably fresh install)

[Alex Murray (alexmurray)]

Thanks for taking the time to report this bug and helping to make Ubuntu better. We appreciate the difficulties you are facing, but this appears to be a "regular" (non-security) bug. I have unmarked it as a security issue since this bug does not show evidence of allowing attackers to cross privilege boundaries nor directly cause loss of data/privacy. Please feel free to report any other bugs you may find.

[Seth Arnold (seth-arnold)]

Hello, possibly related to:

https://bugs.launchpad.net/ubuntu/+bug/1866219

Thanks

[Daniel van Vugt (vanvugt)]

This sounds serious. Can you please report it to the gnome-shell developers at https://gitlab.gnome.org/GNOME/gnome-shell/issues ?

[Daniel van Vugt (vanvugt)]

Also, just in case this is related to the choice of graphics driver please run:

  lspci -k > lspcik.txt

and attach the resulting file here.

[Andrew Kornilov (akornilov)]

HI,

That was my first thought. However, Focal repo does not provide the latest GNOME Shell version, that it might have been already fixed. So i decided to report here first.
So i'll report it now.

[Andrew Kornilov (akornilov)]

lcipcik data

[Andrew Kornilov (akornilov)]

Could some one please test it and confirm? Just disable animation and then lock the screen.
That might be my local issue.

[Andrew Kornilov (akornilov)]

My issue has been marked as duplicate of https://gitlab.gnome.org/GNOME/gnome-shell/issues/2255 which is already fixed 1 week ago.

[Ernst Persson (ernstp)]

This is still happening to me. Enabling animations again solved it.
Could it be related to Yaru GTK theme or Yaru shell theme?

[Ernst Persson (ernstp)]

It should definitively be visible here...
https://errors.ubuntu.com/?release=Ubuntu%2020.04&package=gnome-shell&period=week