/usr/share/lintian/overrides/lightdm-gtk-greeter is in lightdm-gtk-greeter 1.8.4-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | # we do pass -fstack-protector
lightdm-gtk-greeter: hardening-no-stackprotector usr/sbin/lightdm-gtk-greeter
# not really used directly by users
lightdm-gtk-greeter: binary-without-manpage usr/sbin/lightdm-gtk-greeter
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