From: Stephen Smalley <sds@epoch.ncsc.mil>

This patch fixes a couple of bugs in the SELinux policy loading code.  The
first bug was reported by Magosanyi Arpad; kernel panic upon feeding the
kernel a policy with an empty avtab due to cleanup code trying to free the
avtab twice.  The other bugs were reported by Frank Mayer; failure to
properly validate certain values read from the policy.