Bug#985510: systemd: IPv6 Proxy NDP addresses are lost from interfaces after networkd adds them

[Kevin P. Fleming]

Package: systemd
Version: 247.3-3
Severity: normal
Tags: ipv6 upstream patch

Dear Maintainer,

After configuring IPv6 Proxy NDP addresses on a link, and not
receiving any errors, the addresses disappeared from the link during
the system startup process. Restarting systemd-networkd restored the
addresses to the link, and the system operated as expected.

After extensive debugging, it was determined that in some cases during
system startup, a NIC will temporarily lose its 'carrier' (link) status,
and when this happens any previously-configured Proxy NDP addresses
on the link are removed by the kernel networking stack. systemd-networkd
was aware of this state change, but did not re-add the Proxy NDP
addresses to the link.

This was reported and confirmed upstream here:

https://github.com/systemd/systemd/issues/18378

A patch was provided to upstream, and merged here:

https://github.com/systemd/systemd/pull/18494

The patch was also merged to the upstream 'stable' branch here:

https://github.com/systemd/systemd-stable/issues/89

-- Package-specific info:

-- System Information:
Debian Release: bullseye/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 5.10.0-3-amd64 (SMP w/8 CPU threads)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages systemd depends on:
ii  adduser                          3.118
ii  libacl1                          2.2.53-10
ii  libapparmor1                     2.13.6-9
ii  libaudit1                        1:3.0-2
ii  libblkid1                        2.36.1-7
ii  libc6                            2.31-9
ii  libcap2                          1:2.44-1
ii  libcrypt1                        1:4.4.17-1
ii  libcryptsetup12                  2:2.3.4-2
ii  libgcrypt20                      1.8.7-3
ii  libgnutls30                      3.7.0-7
ii  libgpg-error0                    1.38-2
ii  libip4tc2                        1.8.7-1
ii  libkmod2                         28-1
ii  liblz4-1                         1.9.3-1
ii  liblzma5                         5.2.5-1.0
ii  libmount1                        2.36.1-7
ii  libpam0g                         1.4.0-6
ii  libseccomp2                      2.5.1-1
ii  libselinux1                      3.1-3
ii  libsystemd0                      247.3-3
ii  libzstd1                         1.4.8+dfsg-2.1
ii  mount                            2.36.1-7
ii  systemd-timesyncd [time-daemon]  247.3-3
ii  util-linux                       2.36.1-7

Versions of packages systemd recommends:
ii  dbus  1.12.20-2

Versions of packages systemd suggests:
ii  policykit-1        0.105-30
ii  systemd-container  247.3-3

Versions of packages systemd is related to:
pn  dracut           <none>
ii  initramfs-tools  0.139
pn  libnss-systemd   <none>
ii  libpam-systemd   247.3-3
ii  udev             247.3-3

-- Configuration Files:
/etc/systemd/resolved.conf changed [not included]

-- no debconf information