Bug#842499: systemd-sysv: Scroll Lock on VT prevents reboot/shutdown

[Matt Sickler]

Package: systemd-sysv
Version: 215-17+deb8u5
Severity: normal

Dear Maintainer,

I discovered this bug a couple months ago and posted to debian-user (thread there
has the same subject as here) and was directed to file the bug against this package.

I do not have a GUI installed, so the replication is entirely from VTs (though part
of it can be done remotely via SSH).

Here's how to replicate the bug:
    1) Log in as a normal user on a VT/
    2) Start nano.  If nano is not available, I think any application that interacts
       with the user would work, but I've only tried using nano.
    3) Hit Scroll Lock - At this point, anything you type will get buffered somewhere
       and won't show up until you turn off Scroll Lock.  Leave it on for the moment.
    4) Switch to a different VT using Alt+F2  or do these next steps from an SSH session
    5) Run "sudo reboot" or "sudo shutdown"
    6) The system will start rebooting (some services will stop) but it will "hang" in
       the reboot until you go back to the first VT and turn off Scroll Lock.

I have not found a way to prevent the bug from happening.  If you have physical console
access, the obvious solution is to switch to the affect VT and disable scroll lock.
If you only have remote access, then running this will unblock the console:
    sudo stty -F /dev/console ixon ; sudo stty -F /dev/console -ixon
I came across that workaround after digging through the TTY code and seeing this which
made me think to try toggling ixon.  Note that this only works if you already have an
SSH session before initiating the shutdown/reboot - nologin prevents new sessions
from starting otherwise.

In the debian-user thread, two other users were able to confirm that the bug is 
reproducable on their systems, and one reported that it did *not* seem to affect
an old install of Wheezy.



-- System Information:
Debian Release: 8.6
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.16.0-4-amd64 (SMP w/16 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages systemd-sysv depends on:
ii  systemd  215-17+deb8u5

systemd-sysv recommends no packages.

systemd-sysv suggests no packages.

-- no debconf information