[XFRM]: Fix OOPSes in xfrm_audit_log().

Make sure that this function is called correctly, and
add BUG() checking to ensure the arguments are sane.

Based upon a patch by Joy Latten.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index d55436d..2567453 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1273,10 +1273,6 @@
 		xp = xfrm_policy_bysel_ctx(type, p->dir, &p->sel, tmp.security, delete);
 		security_xfrm_policy_free(&tmp);
 	}
-	if (delete)
-		xfrm_audit_log(NETLINK_CB(skb).loginuid, NETLINK_CB(skb).sid,
-			       AUDIT_MAC_IPSEC_DELSPD, (xp) ? 1 : 0, xp, NULL);
-
 	if (xp == NULL)
 		return -ENOENT;
 
@@ -1292,8 +1288,14 @@
 					      MSG_DONTWAIT);
 		}
 	} else {
-		if ((err = security_xfrm_policy_delete(xp)) != 0)
+		err = security_xfrm_policy_delete(xp);
+
+		xfrm_audit_log(NETLINK_CB(skb).loginuid, NETLINK_CB(skb).sid,
+			       AUDIT_MAC_IPSEC_DELSPD, err ? 0 : 1, xp, NULL);
+
+		if (err != 0)
 			goto out;
+
 		c.data.byid = p->index;
 		c.event = nlh->nlmsg_type;
 		c.seq = nlh->nlmsg_seq;