crypto/x509: marshal certificate revocation times in UTC (Zulu time).

This is required by RFC 5280.

Fixes #16686

Change-Id: I291c68dd97410a4f7ae7c4e524b91a2493ac50a9
Reviewed-on: https://go-review.googlesource.com/34245Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/crypto/x509/x509.go

@@ -1850,13 +1850,20 @@ func (c *Certificate) CreateCRL(rand io.Reader, priv interface{}, revokedCerts [
 		return nil, err
 	}
 
+	// Force revocation times to UTC per RFC 5280.
+	revokedCertsUTC := make([]pkix.RevokedCertificate, len(revokedCerts))
+	for i, rc := range revokedCerts {
+		rc.RevocationTime = rc.RevocationTime.UTC()
+		revokedCertsUTC[i] = rc
+	}
+
 	tbsCertList := pkix.TBSCertificateList{
 		Version:             1,
 		Signature:           signatureAlgorithm,
 		Issuer:              c.Subject.ToRDNSequence(),
 		ThisUpdate:          now.UTC(),
 		NextUpdate:          expiry.UTC(),
-		RevokedCertificates: revokedCerts,
+		RevokedCertificates: revokedCertsUTC,
 	}
 
 	// Authority Key Id

src/crypto/x509/x509_test.go

@@ -850,29 +850,47 @@ func TestCRLCreation(t *testing.T) {
 	block, _ = pem.Decode([]byte(pemCertificate))
 	cert, _ := ParseCertificate(block.Bytes)
 
-	now := time.Unix(1000, 0)
+	loc := time.FixedZone("Oz/Atlantis", int((2 * time.Hour).Seconds()))
+
+	now := time.Unix(1000, 0).In(loc)
+	nowUTC := now.UTC()
 	expiry := time.Unix(10000, 0)
 
 	revokedCerts := []pkix.RevokedCertificate{
 		{
 			SerialNumber:   big.NewInt(1),
-			RevocationTime: now,
+			RevocationTime: nowUTC,
 		},
 		{
 			SerialNumber: big.NewInt(42),
+			// RevocationTime should be converted to UTC before marshaling.
 			RevocationTime: now,
 		},
 	}
+	expectedCerts := []pkix.RevokedCertificate{
+		{
+			SerialNumber:   big.NewInt(1),
+			RevocationTime: nowUTC,
+		},
+		{
+			SerialNumber:   big.NewInt(42),
+			RevocationTime: nowUTC,
+		},
+	}
 
 	crlBytes, err := cert.CreateCRL(rand.Reader, priv, revokedCerts, now, expiry)
 	if err != nil {
 		t.Errorf("error creating CRL: %s", err)
 	}
 
-	_, err = ParseDERCRL(crlBytes)
+	parsedCRL, err := ParseDERCRL(crlBytes)
 	if err != nil {
 		t.Errorf("error reparsing CRL: %s", err)
 	}
+	if !reflect.DeepEqual(parsedCRL.TBSCertList.RevokedCertificates, expectedCerts) {
+		t.Errorf("RevokedCertificates mismatch: got %v; want %v.",
+			parsedCRL.TBSCertList.RevokedCertificates, expectedCerts)
+	}
 }
 
 func fromBase64(in string) []byte {