Lightdm-gtk-greeter coredump during boot with recent systemd versions

Moving on to,

# cat /proc/version_signature

Ubuntu 5.8.0-16.17-generic 5.8.0

The bug is still there and greeter dumps core almost 2-3 times in a given boot before stabilizing.

Backtrace: https://termbin.com/yvkg

Thanks, is that in a virtual machine environment?

Trying on gnome-boxes the greeter sigtrap on 20.10, valgrind shows the error there

==2508== Invalid read of size 16
==2508== at 0x4021F4F: strncmp (strcmp.S:857)
==2508== by 0x40069BD: is_dst (dl-load.c:210)
==2508== by 0x40085DE: _dl_dst_count (dl-load.c:247)
==2508== by 0x40085DE: expand_dynamic_string_token (dl-load.c:389)
==2508== by 0x4008787: fillin_rpath.isra.0 (dl-load.c:461)
==2508== by 0x4008AD2: decompose_rpath (dl-load.c:632)
==2508== by 0x400AF9C: cache_rpath (dl-load.c:674)
==2508== by 0x400AF9C: cache_rpath (dl-load.c:655)
==2508== by 0x400AF9C: _dl_map_object (dl-load.c:2161)
==2508== by 0x400F594: openaux (dl-deps.c:64)
==2508== by 0x5A344A7: _dl_catch_exception (dl-error-skeleton.c:208)
==2508== by 0x400FD78: _dl_map_object_deps (dl-deps.c:248)
==2508== by 0x4016265: dl_open_worker (dl-open.c:584)
==2508== by 0x5A344A7: _dl_catch_exception (dl-error-skeleton.c:208)
==2508== by 0x4015B5C: _dl_open (dl-open.c:864)
==2508== by 0x5B0C34B: dlopen_doit (dlopen.c:66)
==2508== by 0x5A344A7: _dl_catch_exception (dl-error-skeleton.c:208)
==2508== by 0x5A34572: _dl_catch_error (dl-error-skeleton.c:227)
==2508== by 0x5B0CB88: _dlerror_run (dlerror.c:170)
==2508== by 0x5B0C3D7: dlopen@@GLIBC_2.2.5 (dlopen.c:87)
==2508== by 0xA88F84D: loader_open_driver (loader.c:563)
==2508== by 0xA86BF84: driOpenDriver (dri_common.c:109)
==2508== by 0xA86D49E: driswCreateScreen (drisw_glx.c:869)
==2508== by 0xA8738FF: AllocAndFetchScreenConfigs (glxext.c:832)
==2508== by 0xA8738FF: __glXInitialize (glxext.c:949)
==2508== by 0xA86FE04: GetGLXPrivScreenConfig (glxcmds.c:174)
==2508== by 0xA86FE04: glXQueryServerString (glxcmds.c:1355)
==2508== by 0x5C79EFC: epoxy_glx_version (in /usr/lib/x86_64-linux-gnu/libepoxy.so.0.0.0)
==2508== by 0x5211664: gdk_x11_screen_init_gl (gdkglcontext-x11.c:873)
==2508== by 0x52119FF: _gdk_x11_screen_update_visuals_for_gl (gdkglcontext-x11.c:1217)
==2508== by 0x521AC87: _gdk_x11_screen_init_visuals (gdkvisual-x11.c:309)
==2508== by 0x5217A8E: _gdk_x11_screen_new (gdkscreen-x11.c:1088)
==2508== by 0x5207323: _gdk_x11_display_open (gdkdisplay-x11.c:1606)
==2508== by 0x51D8417: gdk_display_manager_open_display (gdkdisplaymanager.c:462)
==2508== by 0x4C2A65A: gtk_init_check (gtkmain.c:1109)
==2508== by 0x4C2A65A: gtk_init_check (gtkmain.c:1101)
==2508== by 0x4C2A68C: gtk_init (gtkmain.c:1166)
==2508== by 0x113EA5: main (in /usr/sbin/lightdm-gtk-greeter.bin)
==2508== Address 0x8d183c0 is 1 bytes after a block of size 15 alloc'd
==2508== at 0x483C7F3: malloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==2508== by 0x40202AF: malloc (rtld-malloc.h:56)
==2508== by 0x40202AF: strdup (strdup.c:42)
==2508== by 0x4008A64: decompose_rpath (dl-load.c:607)
==2508== by 0x400AF9C: cache_rpath (dl-load.c:674)
==2508== by 0x400AF9C: cache_rpath (dl-load.c:655)
==2508== by 0x400AF9C: _dl_map_object (dl-load.c:2161)
==2508== by 0x400F594: openaux (dl-deps.c:64)
==2508== by 0x5A344A7: _dl_catch_exception (dl-error-skeleton.c:20...

the error log from the description aren't valid anymore

On Wed, 21 Oct 2020 20:06:17 -0000
Sebastien Bacher <email address hidden> wrote:

> the error log from the description aren't valid anymore
>
> --

Yeah it's still an issue I upgraded yesterday to the latest kernel and in my main Xubuntu system. Not sure what you mean by not valid. I can update them with current coredumps if you need.

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

> https://bugs.launchpad.net/ubuntu/+source/lightdm-gtk-greeter/+bug/1890394

the external website url is giving an error

Hello kortewegdevries, or anyone else affected,

Accepted lightdm-gtk-greeter into groovy-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/lightdm-gtk-greeter/2.0.6-0ubuntu2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-groovy to verification-done-groovy. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-groovy. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

I restarted my computer after installing the updated package, and, for now, it seemed to be working for me

This bug was fixed in the package lightdm-gtk-greeter - 2.0.6-0ubuntu3

---------------
lightdm-gtk-greeter (2.0.6-0ubuntu3) hirsute; urgency=medium

  * debian/patches/git_indicators_loading.patch:
    - don't try loading indicators using upstart
  * debian/patches/git_libexec_atspi.patch:
    - use the correct directory for the atspi service
  * debian/patches/git_new_systemd.patch:
    - disable mlockall, it's leading to the greeter hitting memory errors
      using the new systemd version (lp: #1890394)

 -- Sebastien Bacher <email address hidden> Tue, 27 Oct 2020 12:20:30 +0100

Hello kortewegdevries, or anyone else affected,

Accepted lightdm-gtk-greeter into bionic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/lightdm-gtk-greeter/2.0.5-0ubuntu2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-bionic to verification-done-bionic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-bionic. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

I was impacted by this on 2 VM's I have (while using lightdm-gtk-greeter). Both of them have been upgraded from Xubuntu 20.04 to Xubuntu 20.10. After the update, the effects were as follows:
1) one of the VMs (VMWare) lacked the icons and wallpaper on the greeter page, but functionally, everything was working, I was able to login.
2) one of the VM's (Virtualbox) entered in a loop in which tried to start the lightdm-gtk-greeter 5 times, without success, resulting in a black screen. I checked the logs in /var/log/ligntdm

I was running version 2.0.6-0ubuntu1 on BOTH VM's.
I was able to bypss this by uninstalling lightdm-gtk-greeter and installing unity-greeter.
I enabled the pre-released updates and installed the lightdm-gtk-greeter version 2.0.6-0ubuntu2
Note the 2 at the end.

After installing this newer version of the package, the problem was instantly solved, and I was able to switch back to lightdm-gtk-greeter without any issue. Icons were visible again, wallpaper was visible again, and I did not have a black screen anymore.
I confirm the fix is working, at least for the lightdm-gtk-greeter package.
Thanks for this fix, when the new version will be present in the official channels, I will upgrade to 20.10 all my fleet.

I upgraded my laptop from 20.04.1 to 20.10 using do-release-upgrade and found that icons were missing in lightdm-gtk-greeter. Logs suggested that icon files and background wallpaper could not load due to out of memory errors.

I performed a clean install of 20.10 and the icons were then working but I was faced with a black screen 50% of the time. Logs also showed out of memory errors loading fonts etc. systemd was constantly trying to restart lightdm and failing causing a flickering screen.

I added the proposed channel and installed the lightdm-gtk-greeter_2.0.6-0ubuntu2_amd64.deb package from there. Subsequent reboots of my laptop have all worked as expected without any problems.

Thank you for this updated package. It does appear to fix the problem.

On Thu, 05 Nov 2020 15:20:18 -0000
Andy Whitcroft <email address hidden> wrote:

> Hello kortewegdevries, or anyone else affected,
>
> Accepted lightdm-gtk-greeter into bionic-proposed. The package will
> build now and be available at https://launchpad.net/ubuntu/+source
> /lightdm-gtk-greeter/2.0.5-0ubuntu2 in a few hours, and then in the
> -proposed repository.
>
> Please help us by testing this new package. See
> https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
> to enable and use -proposed. Your feedback will aid us getting this
> update out to other Ubuntu users.
>
> If this package fixes the bug for you, please add a comment to this bug,
> mentioning the version of the package you tested, what testing has been
> performed on the package and change the tag from verification-needed-
> bionic to verification-done-bionic. If it does not fix the bug for you,
> please add a comment stating that, and change the tag to verification-
> failed-bionic. In either case, without details of your testing we will
> not be able to proceed.

Hello sorry for the delay. The original problem mentioned in the bug report has now been fixed for me. Here are the details and attached logs. (I haven't seen ny irregularites.)

lightdm 1.30.0-0ubuntu3.1
lightdm-gtk-greeter 2.0.6-0ubuntu2
lightdm-gtk-greeter-settings 1.2.2-3
systemd 246.6-1ubuntu1
linux 5.8.0-26-generic

Hello sorry for the delay. The original problem mentioned in the bug report has now been fixed for me. Here are the details and attached logs. (I haven't seen any irregularites.)

$ lsb_release -a

Distributor ID: Ubuntu
Description: Ubuntu 18.04.5 LTS
Release: 18.04
Codename: bionic

lightdm 1.26.0-0ubuntu1
lightdm-gtk-greeter 2.0.5-0ubuntu2
lightdm-gtk-greeter-settings 1.2.2-1
systemd 237-3ubuntu10.43
linux 5.4.0-52-generic

Thank you for the verification, I'll be releasing these updates to -updates shortly. Just a quick confirmation question in the meantime: is focal (20.04) unaffected by this bug?

The verification of the Stable Release Update for lightdm-gtk-greeter has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

This bug was fixed in the package lightdm-gtk-greeter - 2.0.6-0ubuntu2

---------------
lightdm-gtk-greeter (2.0.6-0ubuntu2) groovy; urgency=medium

  * debian/patches/git_new_systemd.patch:
    - disable mlockall, it's leading to the greeter hitting memory errors
      using the new systemd version (lp: #1890394)

 -- Sebastien Bacher <email address hidden> Tue, 27 Oct 2020 12:39:07 +0100

I tested the proposed update (2.0.5-0ubuntu2) on Ubuntu bionic and I can confirm that it fixes the issue.

That means the lightdm graphical login screen is now displayed again as expected (and is functional, i.e. logins do work), i.e. the lightdm.service start succeeds again.

Can anyone tell me if focal is affected by this bug or not? Since I don't feel comfortable releasing the bionic part without a focal upload present (if the bug is reproducible there as well).

I don't have access to a machine where Ubuntu Focal is installed.

AFAICS, this issue currently breaks Ubuntu Bionic LTS completely for non-technical users running Lxde (e.g. Lubuntu) who regularly apply updates (as recommended) without a simple work-around being available.

With non-technical users I'm referring to users who aren't comfortable on the command line. That means they can't just log into the console and enable the proposed updates etc.

So I consider this as a pretty serious issue for an LTS release.

Releasing it rather earlier than later would probably lead to less people being affected (i.e. those who haven't installed the latest breaking updates yet).

Hello tested on Focal:

linux 5.4.0-53-generic
systemd 245.4ubuntu3.3
lightdm 1.30.0-0ubuntu3.1
lightdm-gtk-greeter 2.0.6-0ubuntu1

Everything works fine.

-------- Original Message --------
From: "Łukasz Zemczak" <email address hidden>
Sent: November 12, 2020 12:02:00 PM UTC
To: <email address hidden>
Subject: [Bug 1890394] Re: Lightdm-gtk-greeter coredump during boot with recent systemd versions

Can anyone tell me if focal is affected by this bug or not? Since I
don't feel comfortable releasing the bionic part without a focal upload
present (if the bug is reproducible there as well).

--
You received this bug notification because you are subscribed to the bug
report.
https://bugs.launchpad.net/bugs/1890394

Title:
  Lightdm-gtk-greeter coredump during boot with recent systemd versions

Status in lightdm-gtk-greeter package in Ubuntu:
  Fix Released
Status in lightdm-gtk-greeter source package in Bionic:
  Fix Committed
Status in lightdm-gtk-greeter source package in Groovy:
  Fix Released

Bug description:
  * Impact
  The lightdm-gtk-greeter often segfaults on VMs

  * Test case
  - start a xubuntu livesession in a VM and logout
  -> you should get a greeter to log in
  (or install xubuntu in a VM)

  * Regression potential
  the mlockall call was supposed to provide improved security but isn't working, it was already commented out some cycles ago in unity-greeter, upstream and it other distributions

  ------------------

  Upstream:https://github.com/Xubuntu/lightdm-gtk-greeter/issues/77

  This is one of the many core dumps on `journalctl` for a given boot
  (dumps multiple times before starting) :

  **See it on upstream bug report**

  System Details:

  System:
  Kernel: 5.8.0-12-generic x86_64 bits: 64 compiler: N/A Desktop:
  Xfce 4.14.2
  Distro: Ubuntu 20.10 (Groovy Gorilla) (*Proposed)

  lightdm 1.30.0-0ubuntu3.1: amd64
  lightdm-gtk-greeter 2.0.6-0ubuntu1:amd64
  lightdm-gtk-greeter-settings 1.2.2-3
  linux-firmware 1.189
  ------------------------------------------------------
  systemd,systemd-coredump,
  systemd-sysv 245.7-1ubuntu1
  ------------------------------------------------------

  Current Behaviour:

  On boot screen blinks for 2-3 times (probably the segmentation fault)
  but eventually starts after 1-2 minutes.

  Expected Behaviour:

  Greeter would appear properly after boot.

  Note: Some other systemd services are also failing on proposed, not
  sure if related.

  ProblemType: Bug
  DistroRelease: Ubuntu 20.10
  Package: lightdm-gtk-greeter 2.0.6-0ubuntu1
  ProcVersionSignature: Ubuntu 5.8.0-12.13-generic 5.8.0-rc7
  Uname: Linux 5.8.0-12-generic x86_64
  ApportVersion: 2.20.11-0ubuntu43
  Architecture: amd64
  CasperMD5CheckResult: skip
  CurrentDesktop: XFCE
  Date: Wed Aug 5 12:58:44 2020
  InstallationDate: Installed on 2020-04-17 (109 days ago)
  InstallationMedia: Xubuntu 20.04 LTS "Focal Fossa" - Beta amd64 (20200416)
  SourcePackage: lightdm-gtk-greeter
  UpgradeStatus: Upgraded to groovy on 2020-08-04 (0 days ago)

  modified.conffile..etc.lightdm.lightdm-gtk-greeter.conf:
  [greeter]
   indicators = ~ses...

Ok, thank you for checking. Releasing this now o/

This bug was fixed in the package lightdm-gtk-greeter - 2.0.5-0ubuntu2

---------------
lightdm-gtk-greeter (2.0.5-0ubuntu2) bionic; urgency=medium

  * debian/patches/git_new_systemd.patch:
    - disable mlockall, it's leading to the greeter hitting memory errors
      using the new systemd version (lp: #1890394)

 -- Sebastien Bacher <email address hidden> Thu, 05 Nov 2020 15:30:12 +0100