Bug#890445: systemd: systemctl tab-auto-completion freezes the terminal and causes 100% CPU utilization

[J Mo]

Package: systemd
Version: 237-1
Severity: normal

Using tab-auto-completion with systemctl can cause /sbin/init to go to 100% CPU utilization and lock up the terminal. This is probably due to the implementation of it's bash-completion file.

This can be replicated by typing "systemctl start whatever" and then quickly pressing tab a few times.

The result is first that the terminal appears to lock up; no input is accepted from the user. Additionally, CPU usage on the system goes to 100% for a long time, dependent upon how many times the user pressed tab.



-- Package-specific info:

-- System Information:
Debian Release: buster/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.14.0-3-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages systemd depends on:
ii  adduser          3.116
ii  libacl1          2.2.52-3+b1
ii  libapparmor1     2.12-2
ii  libaudit1        1:2.8.2-1
ii  libblkid1        2.30.2-0.3
ii  libc6            2.26-6
ii  libcap2          1:2.25-1.2
ii  libcryptsetup12  2:2.0.0-1
ii  libgcrypt20      1.8.1-4
ii  libgpg-error0    1.27-5
ii  libidn11         1.33-2.1
ii  libip4tc0        1.6.1-2+b1
ii  libkmod2         25-1
ii  liblz4-1         0.0~r131-2+b1
ii  liblzma5         5.2.2-1.3
ii  libmount1        2.30.2-0.3
ii  libpam0g         1.1.8-3.6
ii  libseccomp2      2.3.1-2.1
ii  libselinux1      2.7-2
ii  libsystemd0      237-1
ii  mount            2.30.2-0.3
ii  procps           2:3.3.12-3
ii  util-linux       2.30.2-0.3

Versions of packages systemd recommends:
ii  dbus            1.12.2-1
ii  libpam-systemd  237-1

Versions of packages systemd suggests:
ii  policykit-1        0.105-18
pn  systemd-container  <none>

Versions of packages systemd is related to:
pn  dracut           <none>
ii  initramfs-tools  0.130
ii  udev             237-1

-- no debconf information