[SELINUX]: Fix bug in security_sid_mls_copy

The following fixes a bug where random mem is being tampered with in the
non-mls case; encountered by Jashua Brindle on a gentoo box.

Signed-off-by: Venkat Yekkirala <vyekkirala@TrustedCS.com>
Acked-by:  Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>

security/selinux/ss/services.c

@@ -1841,7 +1841,7 @@ int security_sid_mls_copy(u32 sid, u32 mls_sid, u32 *new_sid)
 	u32 len;
 	int rc = 0;
 
-	if (!ss_initialized) {
+	if (!ss_initialized || !selinux_mls_enabled) {
 		*new_sid = sid;
 		goto out;
 	}