SELinux: add more validity checks on policy load

Add more validity checks at policy load time to reject malformed
policies and prevent subsequent out-of-range indexing when in permissive
mode.  Resolves the NULL pointer dereference reported in
https://bugzilla.redhat.com/show_bug.cgi?id=357541.

Signed-off-by:  Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>

security/selinux/ss/conditional.c

@@ -362,7 +362,8 @@ static int cond_read_av_list(struct policydb *p, void *fp, struct cond_av_list *
 	data.head = NULL;
 	data.tail = NULL;
 	for (i = 0; i < len; i++) {
-		rc = avtab_read_item(fp, p->policyvers, &p->te_cond_avtab, cond_insertf, &data);
+		rc = avtab_read_item(&p->te_cond_avtab, fp, p, cond_insertf,
+				     &data);
 		if (rc)
 			return rc;