[Pkg-shadow-devel] Bug#868568: Possible cause of deluser problem: subordinate user IDs

Ben Harris bjh21 at cam.ac.uk
Tue Mar 8 17:31:41 GMT 2022

I ran into a problem very similar to the one described in Debian bug 
868568: deleting a user with a UID < 100000 failed because of a process 
that was running as a user with a UID >= 100000.  It turned out to be 
because the larger user ID was recorded in /etc/subuid as a subordinate 
user-ID for the lower-numbered user.  Blanking out /etc/subuid and 
/etc/subgid caused deluser to behave as normal.

According to login.defs(5), the default range of subuids starts at 100000. 
If you're using UIDs over 100000 for normal users then you probably want 
to change that (or find a way to disable subordinate user-IDs entirely).

Ben Harris, University of Cambridge Information Services.

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