MFC r332151:

MFC r332151:

ifconf(): correct handling of sockaddrs smaller than struct sockaddr.

Portable programs that use SIOCGIFCONF (e.g. traceroute) assume
that each pseudo ifreq is of length MAX(sizeof(struct ifreq),
sizeof(ifr_name) + ifr_addr.sa_len).  For short sockaddrs we copied
too much from the source sockaddr resulting in a heap leak.

I believe only one such sockaddr exists (struct sockaddr_sco which
is 8 bytes) and it is unclear if such sockaddrs end up on interfaces
in practice.  If it did, the result would be an 8 byte heap leak on
current architectures.

admbugs:	869
Reviewed by:	kib
Obtained from:	CheriBSD
Security:	kernel heap leak
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D14981

git-svn-id: svn://svn.freebsd.org/base/stable/10@332332 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f