crypto/x509: properly handle issuerUniqueID and subjectUniqueID

Fixes #51754

Change-Id: I3bfa15db3497de9fb82d6391d87fca1ae9ba6543
Reviewed-on: https://go-review.googlesource.com/c/go/+/394297
Trust: Roland Shoemaker <roland@golang.org>
Run-TryBot: Roland Shoemaker <roland@golang.org>
Auto-Submit: Roland Shoemaker <roland@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>

Author: rolandshoemaker

src/crypto/x509/parser.go

@@ -941,10 +941,10 @@ func parseCertificate(der []byte) (*Certificate, error) {
 	}
 
 	if cert.Version > 1 {
-		if !tbs.SkipOptionalASN1(cryptobyte_asn1.Tag(1).Constructed().ContextSpecific()) {
+		if !tbs.SkipOptionalASN1(cryptobyte_asn1.Tag(1).ContextSpecific()) {
 			return nil, errors.New("x509: malformed issuerUniqueID")
 		}
-		if !tbs.SkipOptionalASN1(cryptobyte_asn1.Tag(2).Constructed().ContextSpecific()) {
+		if !tbs.SkipOptionalASN1(cryptobyte_asn1.Tag(2).ContextSpecific()) {
 			return nil, errors.New("x509: malformed subjectUniqueID")
 		}
 		if cert.Version == 3 {

src/crypto/x509/x509_test.go

@@ -3348,3 +3348,51 @@ func TestLargeOID(t *testing.T) {
 		t.Fatalf("ParseCertificate to failed to parse certificate with large OID: %s", err)
 	}
 }
+
+const uniqueIDPEM = `-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----`
+
+func TestParseUniqueID(t *testing.T) {
+	b, _ := pem.Decode([]byte(uniqueIDPEM))
+	if b == nil {
+		t.Fatalf("couldn't decode test certificate")
+	}
+	cert, err := ParseCertificate(b.Bytes)
+	if err != nil {
+		t.Fatalf("ParseCertificate to failed to parse certificate with unique identifier id: %s", err)
+	}
+	if len(cert.Extensions) != 7 {
+		t.Fatalf("unexpected number of extensions (probably because the extension section was not parsed): got %d, want 7", len(cert.Extensions))
+	}
+}