linux kernel 4.15.0-44 and 4.15.0-45 break tty login

[David R. Bergstein]

On systems with either version of the kernel installed (4.15.0-44 or 4.15.0-45), login to the console (tty) is not possible. When the prior version, 4.15.0-43, is running this issue does not occur.

1) The release of Ubuntu via 'lsb_release -rd':
Description: Ubuntu 18.04.1 LTS
Release: 18.04

2) The version of the package, via 'apt-cache policy pkgname'
linux-generic:
  Installed: (none)
  Candidate: 4.15.0.45.47
  Version table:
     4.15.0.45.47 500
        500 http://us.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages
     4.15.0.20.23 500
        500 http://us.archive.ubuntu.com/ubuntu bionic/main amd64 Packages

3) What I expected to happen:
Normal login via tty

4) What happened instead
login program would not allow login process to proceed, password prompts were interrupted.

[David R. Bergstein (dbergst)]

Additional information on installed (working) kernel, as the data provided by apt cache did not show it:

linux-image-4.15.0-43-generic/bionic-updates,bionic-security 4.15.0-43.46 i386
linux-image-unsigned-4.15.0-43-generic/bionic-updates,bionic-security 4.15.0-43.46 amd64
linux-modules-4.15.0-43-generic/bionic-updates,bionic-security,now 4.15.0-43.46 amd64 [installed,automatic]
linux-modules-extra-4.15.0-43-generic/bionic-updates,bionic-security,now 4.15.0-43.46 amd64 [installed]

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1814993

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Thomas Dreibholz (dreibh)]

I can confirm the issue. After entering the username, a <Return> seems to add an additional <Return> in the password prompt. This prevents the console login. I can reproduce the issue under multiple Bionic systems. This is really a major issue, since it makes the systems unusable if there is no other way to access them!

The issue seems to have been introduced with 4.15.0-45. For the systems on 4.15.0-45, I cannot log into the consoles any more.

$ uname -a
Linux kringsjaa 4.15.0-45-generic #48-Ubuntu SMP Tue Jan 29 16:28:13 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux