Remove invalid SAN certificate construction

Kubernetes-commit: f40e4ce55298e0d0ea0149987e774b44a276075c

Author: liggitt

util/cert/cert.go

@@ -75,13 +75,15 @@ func NewSelfSignedCACert(cfg Config, key crypto.Signer) (*x509.Certificate, erro
 			CommonName:   cfg.CommonName,
 			Organization: cfg.Organization,
 		},
-		DNSNames:              []string{cfg.CommonName},
 		NotBefore:             notBefore,
 		NotAfter:              now.Add(duration365d * 10).UTC(),
 		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
 		BasicConstraintsValid: true,
 		IsCA:                  true,
 	}
+	if len(cfg.CommonName) > 0 {
+		tmpl.DNSNames = []string{cfg.CommonName}
+	}
 
 	certDERBytes, err := x509.CreateCertificate(cryptorand.Reader, &tmpl, &tmpl, key.Public(), key)
 	if err != nil {