MFS r255435: MFC r255320:

Return BUS_PROBE_DEFAULT instead of BUS_PROBE_SPECIFIC.

Approved by:	re (hrs)
In IPv6 and NetATM, stop SIOCSIFADDR, SIOCSIFBRDADDR, SIOCSIFDSTADDR
and SIOCSIFNETMASK at the socket layer rather than pass them on to the
link layer without validation or credential checks.  [SA-13:12]

Prevent cross-mount hardlinks between different nullfs mounts of the
same underlying filesystem.  [SA-13:13]

Security:	CVE-2013-5691
Security:	FreeBSD-SA-13:12.ifioctl
Security:	CVE-2013-5710
Security:	FreeBSD-SA-13:13.nullfs
Approved by:	re
Reintegrate r250907 (previously reverted as r254754) plus MFS r254947,
r255443:

r250907 (scottl):
  MFC r248830, r250027, r250409: Several fixes and improvements
  to sendfile()

r254947 (kib):
  NFS implementation of VOP_READ() sometimes upgrades the vnode lock,
  which causes drop of the shared lock and sleep for exclusive.  As
  result, busying of the page before the call to vn_rdwr() makes NFS
  code to wait for vnode lock while page is busy, which contradicts the
  proper order of vnode lock -> busy.

r255443 (des):
  Fix the length calculation for the final block of a sendfile(2)
  transmission which could be tricked into rounding up to the nearest
  page size, leaking up to a page of kernel memory.  [13:11]

Approved by:	re (delphij)
Sponsored by:	The FreeBSD Foundation
Update releng/9.2 to -RC4.

Approved by:	re (implicit)