MFC r280331:

cred: add proc_set_cred_init helper

PR: D7431

MFC r298819:

sys/kern: spelling fixes in comments.

MFC r280130:

cred: add proc_set_cred helper

o Fix SCTP ICMPv6 error message vulnerability. [SA-16:01.sctp]
o Fix Linux compatibility layer incorrect futex handling. [SA-16:03.linux]
o Fix Linux compatibility layer setgroups(2) system call. [SA-16:04.linux]
o Fix TCP MD5 signature denial of service. [SA-16:05.tcp]
o Fix insecure default bsnmpd.conf permissions. [SA-16:06.bsnmpd]

Security: FreeBSD-SA-16:01.sctp, CVE-2016-1879
Security: FreeBSD-SA-16:03.linux, CVE-2016-1880
Security: FreeBSD-SA-16:04.linux, CVE-2016-1881
Security: FreeBSD-SA-16:05.tcp, CVE-2016-1882
Security: FreeBSD-SA-16:06.bsnmpd, CVE-2015-5677

MFC r277322:
Add procctl(2) PROC_TRACE_CTL command to enable or disable debugger
attachment to the process.

[SA-14:25] Fix kernel stack disclosure in setlogin(2) / getlogin(2).
[SA-14:26] Fix remote command execution in ftp(1).

Approved by: so (des)

MFC r277322:
Add procctl(2) PROC_TRACE_CTL command to enable or disable debugger
attachment to the process.

[SA-14:25] Fix kernel stack disclosure in setlogin(2) / getlogin(2).
[SA-14:26] Fix remote command execution in ftp(1).

Approved by: so (des)