Comment 0 for bug 1876600

[Impact]
Long-running services overflow the sd_bus->cookie counter, causing further communication with org.freedesktop.systemd1 to stall.

[Description]
Systemd dbus messages usually include a "cookie" value to uniquely identify them in their bus context. For services that run for longer periods of time and keep communicating through dbus, it's possible to overflow the cookie value, causing further messages to the org.freedesktop.systemd1 dbus to hang.

This has been fixed upstream by the commit below:
- sd-bus: deal with cookie overruns (1f82f5bb4237)

$ git describe --contains 1f82f5bb4237
v242-rc1~228

$ rmadison systemd
 systemd | 229-4ubuntu4 | xenial | source, ...
 systemd | 229-4ubuntu21.27 | xenial-security | source, ...
 systemd | 229-4ubuntu21.27 | xenial-updates | source, ...
 systemd | 229-4ubuntu21.28 | xenial-proposed | source, ...
 systemd | 237-3ubuntu10 | bionic | source, ...
 systemd | 237-3ubuntu10.38 | bionic-security | source, ...
 systemd | 237-3ubuntu10.39 | bionic-updates | source, ...
 systemd | 237-3ubuntu10.40 | bionic-proposed | source, ... <----
 systemd | 242-7ubuntu3 | eoan | source, ...

Releases starting with Eoan already have this fix.

[Test Case]
There doesn't seem to be an easy test case for this, as the cookie values start at zero and won't overflow until (1<<32). There have been reports from users hitting this on Kubernetes clusters continuously running for longer periods (~5 months).