LM MATE 19 Screensaver (1.20.0-1) Unlocks When Monitor is Switched Off

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LM MATE 19 Screensaver (1.20.0-1) Unlocks When Monitor is Switched Off

Post by mithrenithil »

Hi all

I found a nasty bug when I migrated all my kit to LM MATE 19 last week. I found that my personal home setup 2 of my LM19 workstations would unlock by themselves and I was not able to lock them unless I killed and restarted mate-screensaver. mate-screensaver (1.20.0-1) was still running so it wasn't defunct or zombied, just not responding to a manual lock or to the inactivity timeout.

I finally narrowed it down to when I shut down my Win10 gaming box and the Lindy USB/HDMI KVM will send a monitor shutdown command to all the devices plugged into it.

After much Googling I found this bug:

https://bugs.launchpad.net/ubuntu/+sour ... ug/1768352

The issue has been found and patched in Ubuntu 18.10, but they are still dilly dallying being cautious about pushing into 18.04...

So as a short term mitigation I tried the Cosmic version of mate-screensaver and mate-screensaver-common (1.20.2-1) and that seems to have fixed the problem.

I've tested it on 3 different machines so far (only amd64 I'm afraid).

If you want to avoid someone easily bypassing your screensaver lock by switching off and on your monitor download the following:

mate-screensaver (1.20.2-1)
mate-screensaver-common (1.20.2-1)

from the Ubuntu 18.10 (Cosmic) repo:

https://launchpad.net/ubuntu/disco/+pac ... creensaver

Then install with (example of install the amd64 version):

Code: Select all

sudo dpkg -i mate-screensaver-common_1.20.2-1_all.deb mate-screensaver_1.20.2-1_amd64.deb
You will most likely need to restart your PC (or at least hup mate-screensaver) after updating the above packages.

Once they have pushed the fixed packages into 18.04 I plan to reinstall the proper packages with:

Code: Select all

sudo apt install --reinstall mate-screensaver-common mate-screensaver
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Re: LM MATE 19 Screensaver (1.20.0-1) Unlocks When Monitor is Switched Off

Post by randomguy »

A proposed DEB package for Ubuntu 18.04 can be found here:

https://launchpad.net/~ubuntu-security- ... d/15713894

I had 1.20.0-1 and MATE 19.1 screen wouldn't lock upon closing the lid of my laptop and Menu > Lock Screen wouldn't do anything. (Strangely, I think I didn't have this problem few days ago, I spotted it just today - maybe because until today I didn't take this laptop out so I never paid attention).

Anyway, after upgrading to 1.20.2 now Menu > Lock Screen locks the screen. I haven't yet tried to suspend, but at least I can manually lock my screen.

Edit: I discovered a new problem - if the screen is left locked for a while (perhaps until Screen Sleep or some other timeout), I can't get Login window to appear. I had to SSH to the system and kill screensaver.
I went back to 1.20.0-1, removed screensavers and installed the (basic aka ugly) xscreensaver (5.36-1ubuntu1) and in Settings > Screensaver set the screen to auto-lock. I get the basic login screen (doesn't look very nice, but it works) and this also works from Mint Mate menu (Lock Screen). There's a fair number of bugs in this area https://bugs.launchpad.net/ubuntu?field ... saver+lock)
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