Public bug reported:

This report is tracking a possible regression caused by the recent
CVE-2018-1116 patches to policykit-1.

On 18.04, since package upgrades on July 23rd, and after the first
reboot since then on Aug 1st, I hit an issue with the primary (sudo,
adm, etc...) user getting Permission Denied trying to do:

tail -f /var/log/syslog

when that file is owned by syslog:adm and is g=r.

I then found that "groups" reports only the $USER and not the entire
list, but "groups $USER" reports all the groups correctly.

The user shell is set to /usr/bin/tmux and /etc/tmux.conf has "set -g
default-shell /bin/bash"

After changing the user's shell back to /bin/bash and logging in on tty1
the list of groups shows correctly for the /bin/bash process running on
tty1.

I investigated and found that for the affected processes, such as the
tmux process, /proc/$PID/loginuid = 4294967295  whereas the /bin/bash
process on tty1 correctly reported 1000. The same with the respective
gid_map and uid_map.

4294967295 == -1 == 0xFFFFFFFF

The recent CVE patch to policykit has several functions where it does
"uid = -1" which seems to tie in to my findings so far.

** Affects: policykit-1 (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1784964

Title:
  Regression due to CVE-2018-1116 (processes not inheriting user ID or
  groups )

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