in particular, if the old environment is NULL.
Among making it less surprising for userspace to observe NULL environ,
the change also prevents NULL deref in __rebuild_environ() when
terminating the empty as NULL environment with the NULL pointer.
Reported by: Leo Bicknell <[email protected]>
PR: 298747
Reviewed by: emaste, markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D59996
Konstantin Belousov
dec68aeff8