The manager_dispatch_notify_fd function in systemd allows local users to cause a denial of service (system hang) via a zero-length message received over a notify socket, which causes an error to be returned and the notification handler to be disabled.
lists.opensuse.org/opensuse-security-announce/2016-10/msg00015.html
lists.opensuse.org/opensuse-security-announce/2016-10/msg00016.html
rhn.redhat.com/errata/RHSA-2017-0003.html
www.openwall.com/lists/oss-security/2016/09/30/1
www.securityfocus.com/bid/93250
www.securitytracker.com/id/1037320
bugzilla.redhat.com/show_bug.cgi?id=1381911
github.com/systemd/systemd/issues/4234#issuecomment-250441246
rhn.redhat.com/errata/RHBA-2015-2092.html
www.agwa.name/blog/post/how_to_crash_systemd_in_one_tweet