DHCPv6 too strict when the response is missing IAID for some sections

[Ole Markus With]

Systemd incorrectly ignores whole messages when IAID is missing for some sections.
This has been reported upstream [1] and fixed [2].

$ lsb_release -rd
Description: Ubuntu 21.04
Release: 21.04

 $ apt-cache policy systemd
systemd:
  Installed: 247.3-3ubuntu3.6
  Candidate: 247.3-3ubuntu3.6
  Version table:
 *** 247.3-3ubuntu3.6 500
        500 http://no.archive.ubuntu.com/ubuntu hirsute-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     247.3-3ubuntu3.4 500
        500 http://security.ubuntu.com/ubuntu hirsute-security/main amd64 Packages
     247.3-3ubuntu3 500
        500 http://no.archive.ubuntu.com/ubuntu hirsute/main amd64 Packages

What is expected to happen is that systemd will ignore only the relevant part of the message, not the entire message.

What is happening is that the entire message is ignored, leading to DHCP leases not being renewed. This is fairly easy to replicate e.g in AWS by enabling both an IPv6 prefix and an IPv6 single address to the same interface.

[1] https://github.com/systemd/systemd/issues/20803
[2] https://github.com/systemd/systemd/pull/20807

[Launchpad Janitor (janitor)]

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

[Ciprian Hacman (chacman)]

This is bug is blocking any experiments with AWS prefixes because DHCP stops working when such prefixes are assigned to the interface.

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "Cherry-pick from upstream" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issues please contact him.]

[Ciprian Hacman (chacman)]

Patch for this issue was cherry-picked and merged into systemd/systemd-stable:
- v249 - https://github.com/systemd/systemd-stable/pull/134
- v248 - https://github.com/systemd/systemd-stable/pull/135
- v247 - https://github.com/systemd/systemd-stable/pull/136

[Nick Rosbrook (enr0n)]

The upstream commit (https://github.com/systemd/systemd/commit/469fd57f181e2a8d93f01662418ca998e1239ea5) was backported to v249.6 (a while ago), so this is fixed in Jammy and newer.