Bug#927833: gnome-shell: any user can definitely freeze a seat, preventing any VT switch

[Ludovic Pouzenc]

Package: gnome-shell
Version: 3.32.1-1
Severity: normal

Dear Maintainer,

While trying to get trace for #927831, I realized that any user that 
have an active gnome3 wayland session could lock-up the whole seat, 
preventing any VT switch just by starting a gnome-terminal and typing :

ludovic at lud-mn1:~$ kill -SIGSTOP $(pidof gnome-shell)

The only thing I can think of to get unstuck is :

  * force poweroff with button
  * Alt + PrintScrn + B (magic keys for sysrq "reBoot")

Resulting in loose all things (files) opened by all (others) users.

It could been seen as a defect in user input event loop processing at a 
global scope. It could be seen as security related.

Regards,
Ludovic