Re: git: 1055bedbed42 - main - pw: Don't return a pointer to an on-stack buffer from grp_set_passwd.

From: Brooks Davis <brooks_at_freebsd.org>
Date: Thu, 08 Dec 2022 23:40:16 UTC 
On Mon, Dec 05, 2022 at 12:30:34AM +0000, John Baldwin wrote:
> The branch main has been updated by jhb:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=1055bedbed42dc176468b45b4f167a752ed8868f
> 
> commit 1055bedbed42dc176468b45b4f167a752ed8868f
> Author:     John Baldwin <jhb@FreeBSD.org>
> AuthorDate: 2022-12-05 00:28:22 +0000
> Commit:     John Baldwin <jhb@FreeBSD.org>
> CommitDate: 2022-12-05 00:28:22 +0000
> 
>     pw: Don't return a pointer to an on-stack buffer from grp_set_passwd.
>     
>     Make 'line' static to move it to .bss instead as that pattern is used
>     elsewhere in pw(8) (e.g. the static buffer in pw_pwcrypt).

It continues to astonish me that compilers allow stack pointers to
be returned at any warning level.  I think casting the result away
completely might manage not to be undefined behavior, but even a dead
store is UB.

-- Brooks