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

[Ben Harris]

On Tue, 8 Mar 2022, Serge E. Hallyn wrote

> So deluser was doing the right thing, right?
>
> The bug is how you got into this state?  Either the adduser for
> the high uid should have checked for it being a delegated subuid,
> or the adduser which added the subuids to the lower subuid should
> have refused when the higher subuid existed as a uid.

As far as I can see, there is no checking for collisions in either 
direction: useradd depends on the ranges [UID_MIN,UID_MAX] and 
[SUB_UID_MIN,SUB_UID_MAX] not overlapping, and issues a warning if you 
assign a static UID outside the specified range.

-- 
Ben Harris, University of Cambridge Information Services.