K 10
svn:author
V 5
jamie
K 8
svn:date
V 27
2021-02-19T21:46:31.145188Z
K 7
svn:log
V 691
MFC jail: Handle a possible race between jail_remove(2) and fork(2)

jail_remove(2) includes a loop that sends SIGKILL to all processes
in a jail, but skips processes in PRS_NEW state.  Thus it is possible
the a process in mid-fork(2) during jail removal can survive the jail
being removed.

Add a prison flag PR_REMOVE, which is checked before the new process
returns.  If the jail is being removed, the process will then exit.
Also check this flag in jail_attach(2) which has a similar issue.

Reported by:    trasz
Approved by:    kib

(cherry picked from commit cc7b73065302005ebc4a19503188c8d6d5eb923d)

Git Hash:   f7007a7d05255a6859dea0982b1f0a6d695e8881
Git Author: jamie@FreeBSD.org
END