commit 83d04c39 upstream.

Fixes kfree of the sadb buffer when it's NULL.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
BugLink: http://bugs.launchpad.net/bugs/1402714
(backported from commit 83d04c39)
Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>