[Bug 1992731] Re: The cursor can be freely moved around and used to erase characters on the TTY while at the login prompt

[Alkis Georgopoulos]

Reproduced in Ubuntu 22.04 and 20.04.
Could NOT reproduce in Ubuntu 18.04.

I think the problem is in `agetty` though, not in `login`.
Added `util-linux` to affected packages.

** Also affects: util-linux (Ubuntu)
   Importance: Undecided
       Status: New

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Title:
  The cursor can be freely moved around and used to erase characters on
  the TTY while at the login prompt

Status in shadow package in Ubuntu:
  New
Status in util-linux package in Ubuntu:
  New

Bug description:
  Welp, this is a weird one. Known to affect Ubuntu Server and multiple
  flavors of Ubuntu.

  Steps to reproduce:

  1: If you are shown a graphical login prompt (e.g. GDM or SDDM), switch to a TTY.
  2. At the login prompt, press the up arrow key twice.
  3: Press Backspace twice.
  4: Press Enter.

  Expected result: Nothing should happen, or possibly key codes should
  appear when the arrow keys are pressed, and those key codes should be
  erased when backspace is pressed.

  Actual result: The cursor moves up two lines when the up arrow key is
  pressed twice, and the "." and "4" of "22.04.1" are erased when
  Backspace is pressed twice. Upon pressing Enter, the TTY seems to
  freeze (no user input causes anything to happen), then the login
  prompt reverts back to its original state and the cursor assumes its
  proper location.

  Notes:
  This bug was first reported by a user named Liver_K on IRC as happening on Ubuntu Server 22.04 after upgrading from 20.04. alkisg then confirmed it on Ubuntu MATE 22.04, and I confirmed it on Kubuntu Focus Suite 22.04.

  Yes, you can indeed use this to erase everything in the TTY screen and
  leave the cursor in the upper-left corner as if the system was stuck.
  Pressing Enter resolves it after a while.

  ProblemType: Bug
  DistroRelease: Ubuntu 22.04
  Package: login 1:4.8.1-2ubuntu2
  ProcVersionSignature: Ubuntu 5.17.0-1017.18-oem 5.17.15
  Uname: Linux 5.17.0-1017-oem x86_64
  ApportVersion: 2.20.11-0ubuntu82.1
  Architecture: amd64
  CasperMD5CheckResult: pass
  CurrentDesktop: KDE
  Date: Thu Oct 13 00:44:03 2022
  InstallationDate: Installed on 2022-10-04 (8 days ago)
  InstallationMedia: Kubuntu 22.04.1 LTS "Jammy Jellyfish" (20220916)
  SourcePackage: shadow
  UpgradeStatus: No upgrade log present (probably fresh install)

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