Public bug reported:
When I enable fingerprint logins (libpam-fprintd), try to login using
lightdm, and the fingerprint login and password login fail, I have to
wait a long time before lightdm prompts for another login attempt. I
don't have this problem with failed logins in other contexts, so the
problem appears to be lightdm specific. I don't know how this is
possible, since PAM is defining the relevant delays.
More details: lightdm waits for TIMEOUT from the timeout=TIMEOUT setting
for the pam_fprintd.so line in /etc/common-auth, which defaults to 10
seconds
auth [success=3 default=ignore] pam_fprintd.so max-
tries=1 timeout=10 # debug
instead of the DELAY from the delay=DELAY setting for pam_faildelay.so in
/etc/pam.d/login, which defaults to 3 seconds
auth optional pam_faildelay.so delay=3000000
I've verified that changing the timeout=TIMEOUT setting for pam_fprintd.so
results in a corresponding change in the delay I experience in lightdm. As far
as I can tell, only lightdm is affected, since if I fail both fingerprint and
password logins in other contexts -- e.g. vtty logins (CTRL+ALT+F1), sudo in a
terminal, and the GUI password prompt when running ubuntu-bug -- I only
experience the 3 second pam_faildelay.so delay.
ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: lightdm 1.30.0-0ubuntu5
ProcVersionSignature: Ubuntu 6.8.0-65.68~22.04.1-generic 6.8.12
Uname: Linux 6.8.0-65-generic x86_64
ApportVersion: 2.20.11-0ubuntu82.10
Architecture: amd64
CasperMD5CheckMismatches: ./.disk/casper-uuid-oem ./boot/grub/efi.img
./boot/grub/grub.cfg ./casper/initrd
CasperMD5CheckResult: fail
CurrentDesktop: GNOME-Flashback:GNOME
Date: Fri Sep 19 13:31:19 2025
DistributionChannelDescriptor:
# This is the distribution channel descriptor for the OEM CDs
# For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
canonical-oem-sutton-jammy-amd64-20240613-884
InstallationDate: Installed on 2024-06-28 (447 days ago)
InstallationMedia: Ubuntu 22.04 LTS "Jammy Jellyfish" -
pc-sutton-jammy-amd64-20240613-884
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)
** Affects: lightdm (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug jammy
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https://bugs.launchpad.net/bugs/2125176
Title:
Lightdm: extra long failed password delay when fingerprint login
enabled
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