systemd-network installs adjacency routes to DNS servers from DHCP even if they're off-net

[Philip Prindeville]

This is a known issue upstream:

https://github.com/systemd/systemd/issues/28495

and indeed a fix is milestoned for v255:

https://github.com/systemd/systemd/pull/28508

It would be good to see this in the next backports build.

Note: this bug only manifests when the DHCP server is sending you a list of DNS servers (fairly common) as well as static-classless-routes (option 121... much less common).

Description: Ubuntu 22.04.2 LTS
Release: 22.04

systemd:
  Installed: 249.11-0ubuntu3.9
  Candidate: 249.11-0ubuntu3.9
  Version table:
 *** 249.11-0ubuntu3.9 500
        500 http://us.archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     249.11-0ubuntu3.7 500
        500 http://security.ubuntu.com/ubuntu jammy-security/main amd64 Packages
     249.11-0ubuntu3 500
        500 http://us.archive.ubuntu.com/ubuntu jammy/main amd64 Packages

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: systemd 249.11-0ubuntu3.9
ProcVersionSignature: Ubuntu 5.15.0-76.83-generic 5.15.99
Uname: Linux 5.15.0-76-generic x86_64
ApportVersion: 2.20.11-0ubuntu82.5
Architecture: amd64
CasperMD5CheckResult: unknown
Date: Wed Jul 26 16:57:28 2023
InstallationDate: Installed on 2017-02-28 (2339 days ago)
InstallationMedia: Ubuntu 16.04.2 LTS "Xenial Xerus" - Release amd64 (20170215.2)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Lsusb-t:
 /: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/15p, 5000M
 /: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/15p, 480M
MachineType: Red Hat KVM
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.15.0-76-generic root=/dev/mapper/ubuntu--vg-root ro crashkernel=384M-:128M crashkernel=384M-:128M crashkernel=384M-:128M crashkernel=384M-2G:128M,2G-:256M crashkernel=384M-2G:128M,2G-:256M crashkernel=384M-2G:128M,2G-:256M crashkernel=384M-:128M crashkernel=384M-:128M crashkernel=384M-:128M crashkernel=384M-:128M crashkernel=512M-:192M
RebootRequiredPkgs: Error: path contained symlinks.
SourcePackage: systemd
SystemdFailedUnits:
 Error: command ['systemctl', 'status', '--full', '●'] failed with exit code 4: Invalid unit name "●" escaped as "\xe2\x97\x8f" (maybe you should use systemd-escape?).
 Unit \xe2\x97\x8f.service could not be found.
 ------
 Error: command ['systemctl', 'status', '--full', '●'] failed with exit code 4: Invalid unit name "●" escaped as "\xe2\x97\x8f" (maybe you should use systemd-escape?).
 Unit \xe2\x97\x8f.service could not be found.
UpgradeStatus: Upgraded to jammy on 2022-09-07 (322 days ago)
dmi.bios.date: 04/01/2014
dmi.bios.release: 0.0
dmi.bios.vendor: SeaBIOS
dmi.bios.version: 1.16.1-1.el9
dmi.board.name: RHEL
dmi.board.vendor: Red Hat
dmi.board.version: RHEL-9.2.0 PC (Q35 + ICH9, 2009)
dmi.chassis.type: 1
dmi.chassis.vendor: Red Hat
dmi.chassis.version: RHEL-9.2.0 PC (Q35 + ICH9, 2009)
dmi.modalias: dmi:bvnSeaBIOS:bvr1.16.1-1.el9:bd04/01/2014:br0.0:svnRedHat:pnKVM:pvrRHEL-9.2.0PC(Q35+ICH9,2009):rvnRedHat:rnRHEL:rvrRHEL-9.2.0PC(Q35+ICH9,2009):cvnRedHat:ct1:cvrRHEL-9.2.0PC(Q35+ICH9,2009):sku9.2.0:
dmi.product.family: Red Hat Enterprise Linux
dmi.product.name: KVM
dmi.product.sku: 9.2.0
dmi.product.version: RHEL-9.2.0 PC (Q35 + ICH9, 2009)
dmi.sys.vendor: Red Hat

[Launchpad Janitor (janitor)]

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