Security researcher and MateSSL founder, Andrew Ayer has uncovered a bug which will either crash or make systemd unstable (depending on who you talk to) on pretty much every linux distro. David Strauss posted a highly critical response to Ayer. In true pedantic nerd-fight fashion there is a bit of back and forth between them over the "true" severity of the issue and what not.
Nerd fights aside, how you feel about this bug, will probably largely depend on how you feel about systemd in general.
The following command, when run as any user, will crash systemd:
NOTIFY_SOCKET=/run/systemd/notify systemd-notify ""
After running this command, PID 1 is hung in the
pause
system call. You can no longer start and stop daemons. inetd-style services no longer accept connections. You cannot cleanly reboot the system. The system feels generally unstable (e.g. ssh and su hang for 30 seconds since systemd is now integrated with the login system). All of this can be caused by a command that's short enough to fit in a Tweet.Edit (2016-09-28 21:34): Some people can only reproduce if they wrap the command in a
while true
loop. Yay non-determinism!
(Score: 2) by hopp on Wednesday October 05 2016, @07:06PM
It was the inclusion of systemd which made me take another look at FreeBSD for our systems. We left FreeBSD when the whole 4-5 upgrade debacle happened and happily returned to FreeBSD when systemd became the standard. bhyve is actually a pretty nice way to layer vm over the zfs and upgrades and auditing are a breeze.
We're a tiny shop so we matter to no one and we may go back to linux some day but for now BSD is our best option.