[Bug 1886115] Re: libseccomp 2.4.3-1ubuntu3.18.04.2 causes systemd to segfault on boot

Fri Jul 3 06:20:12 UTC 2020

I am confused - in the initial bug report you mention
/etc/systemd/system/dbus-org.freedesktop.resolve1.service as the systemd
unit but now you also mention /etc/systemd/system/dbus-
org.freedesktop.ModemManager1.service - can you confirm which one you
have had to disable the SystemCallFilter?

Also there appear to be a bunch of systemd managed services which have
failed to run - could you perhaps downgrade libseccomp back to the
previous version and see if this resolves the issue? I think this would
be a better solution *for now* than disabling the syscall filter (plus
it will help confirm whether this is definitely a causal factor).

sudo apt install libseccomp=2.4.1-0ubuntu0.18.04.2

The other option to try and help debug this would be to try and capture a more complete stack trace of the crash - perhaps something like the following might be enough:

1. Ensure the likely offending version of libseccomp is installed (2.4.3-1ubuntu3.18.04.2) (if you downgraded it above)
2. Uncomment out the SystemCallFilter line from the systemd unit
3. Restart the systemd unit (do not reboot) (assuming it is the dbus one you first mentioned):
  sudo systemctl restart dbus-org.freedesktop.resolve1.service

Then with any luck if systemd does crash it at least not be during boot
- and apport should catch the crash and create a crash dump. Then you
should be able to report this (either as a separate bug or you could
attach it to this bug via `apport-bug /var/crash/<crash-dump.crash>`

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https://bugs.launchpad.net/bugs/1886115

Title:
  libseccomp 2.4.3-1ubuntu3.18.04.2 causes systemd to segfault on boot

Status in libseccomp package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  New

Bug description:
    After applying updates to Ubuntu 18.04 my desktop (apple mini with
  i5-2415M CPU) failed to complete the boot process.  A few seconds into
  the boot, the last message displayed is "/var mounted".  The system
  then appears to hang indefinitely.

    Luckily, the 'rescue' boot image allows the boot process to proceed sufficiently far to allow a root shell to be spawned.  Unfortunately no log files were written during the unsuccessful attempts to boot.  Spawning a 2nd root shell (# nohup getty tty5) on a 2nd virtual terminal (tty5) I was able to observe the message 'systemd freezing execution' after I closed the first root shell and resumed the boot process.  Further a core file was created (belonging to /sbin/init) in the root fs
  --8<--
  (gdb) bt
  #0  0x00007f16807ba187 in kill () at ../sysdeps/unix/syscall-template.S:78
  #1  0x0000563b957223b7 in ?? ()
  #2  <signal handler called>
  #3  __GI___libc_free (mem=0x4a60d140dfd9a5) at malloc.c:3103
  #4  0x0000563b9577c22e in ?? ()
  #5  0x0000563b957672d6 in ?? ()
  #6  0x0000563b9576ba22 in ?? ()
  #7  0x0000563b9574f51a in ?? ()
  #8  0x00007f16803a509a in ?? () from /lib/systemd/libsystemd-shared-237.so
  #9  0x00007f16803a53ea in sd_event_dispatch () from /lib/systemd/libsystemd-shared-237.so
  #10 0x00007f16803a5579 in sd_event_run () from /lib/systemd/libsystemd-shared-237.so
  #11 0x0000563b9572a49d in ?? ()
  #12 0x0000563b9571560c in ?? ()
  #13 0x00007f168079cb97 in __libc_start_main (main=0x563b957139c0, argc=3, argv=0x7ffe78153758, 
      init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, 
      stack_end=0x7ffe78153748) at ../csu/libc-start.c:310
  #14 0x0000563b957164fa in ?? ()
  (gdb) 
  -->8--
   and the kernel message buffer lists 
  --8<--
  traps: systemd[1] general protection fault ip:7f17ebf6e98d sp:7ffd774d6020 error:0 in libc-2.27.so[7f17ebed7000+1e7000]
  -->8--
  . 

    To me that looked a bit like Bug 669702 of Gentoo
  (https://bugs.gentoo.org/669702) and indeed one of the (few) updates
  applied just prior the reboot was the update of libseccomp.

    I was able to circumvent the problem by disabling (commenting out) the syscall filtering requested by systemd (on my system, only /etc/systemd/system/dbus-org.freedesktop.resolve1.service needed to be modified).
  --- 
  ProblemType: Bug
  ApportVersion: 2.20.9-0ubuntu7.15
  Architecture: amd64
  CurrentDesktop: MATE
  DistroRelease: Ubuntu 18.04
  InstallationDate: Installed on 2019-03-30 (460 days ago)
  InstallationMedia: Ubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210)
  MachineType: Apple Inc. Macmini5,1
  NonfreeKernelModules: wl
  Package: systemd 237-3ubuntu10.41 [modified: lib/systemd/system/systemd-resolved.service]
  PackageArchitecture: amd64
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.3.0-62-generic root=UUID=891c2e06-2b40-4e79-a57f-6e550be932bb ro recovery nomodeset
  ProcVersionSignature: Ubuntu 5.3.0-62.56~18.04.1-generic 5.3.18
  Tags:  bionic
  Uname: Linux 5.3.0-62-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm cdrom dialout dip lpadmin plugdev sambashare sudo
  _MarkForUpload: True
  dmi.bios.date: 01/24/2012
  dmi.bios.vendor: Apple Inc.
  dmi.bios.version: MM51.88Z.0077.B10.1201241549
  dmi.board.asset.tag: Base Board Asset Tag#
  dmi.board.name: Mac-8ED6AF5B48C039E1
  dmi.board.vendor: Apple Inc.
  dmi.board.version: Macmini5,1
  dmi.chassis.type: 16
  dmi.chassis.vendor: Apple Inc.
  dmi.chassis.version: Mac-8ED6AF5B48C039E1
  dmi.modalias: dmi:bvnAppleInc.:bvrMM51.88Z.0077.B10.1201241549:bd01/24/2012:svnAppleInc.:pnMacmini5,1:pvr1.0:rvnAppleInc.:rnMac-8ED6AF5B48C039E1:rvrMacmini5,1:cvnAppleInc.:ct16:cvrMac-8ED6AF5B48C039E1:
  dmi.product.family: Macmini
  dmi.product.name: Macmini5,1
  dmi.product.sku: System SKU#
  dmi.product.version: 1.0
  dmi.sys.vendor: Apple Inc.
  --- 
  ProblemType: Bug
  ApportVersion: 2.20.9-0ubuntu7.15
  Architecture: amd64
  CurrentDesktop: MATE
  Dependencies:
   gcc-8-base 8.4.0-1ubuntu1~18.04
   libc6 2.27-3ubuntu1
   libgcc1 1:8.4.0-1ubuntu1~18.04
  DistroRelease: Ubuntu 18.04
  InstallationDate: Installed on 2019-03-30 (460 days ago)
  InstallationMedia: Ubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210)
  NonfreeKernelModules: wl
  Package: libseccomp2 2.4.3-1ubuntu3.18.04.2
  PackageArchitecture: amd64
  ProcVersionSignature: Ubuntu 5.3.0-62.56~18.04.1-generic 5.3.18
  Tags:  bionic
  Uname: Linux 5.3.0-62-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm cdrom dialout dip lpadmin plugdev sambashare sudo
  _MarkForUpload: True

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