commit c4cd8c64cd0a0b2202485587859c7f51a0bac4e2
author Hanno Becker <hanno.becker@arm.com> Wed Sep 13 12:00:15 2017 +0100
committer Hanno Becker <hanno.becker@arm.com> Wed Oct 04 14:34:14 2017 +0100
tree bab142675b09968345d95829efdfeb14ee0f0e63
parent e3af3afd5ac4cd40f1e561bd8fbad545d5495770

Don't add extensions for X.509 non-v3 certificates

This commit removes extension-writing code for X.509 non-v3 certificates from
mbedtls_x509write_crt_der. Previously, even if no extensions were present an
empty sequence would have been added.

library/x509write_crt.c

diff --git a/library/x509write_crt.c b/library/x509write_crt.c
index c807533..c178e88 100644
--- a/library/x509write_crt.c
+++ b/library/x509write_crt.c
@@ -332,13 +332,18 @@
     /*
      *  Extensions  ::=  SEQUENCE SIZE (1..MAX) OF Extension
      */
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_extensions( &c, tmp_buf, ctx->extensions ) );
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED |
-                                                    MBEDTLS_ASN1_SEQUENCE ) );
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC |
-                                                    MBEDTLS_ASN1_CONSTRUCTED | 3 ) );
+
+    /* Only for v3 */
+    if( ctx->version == 2 )
+    {
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_extensions( &c, tmp_buf, ctx->extensions ) );
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED |
+                                                           MBEDTLS_ASN1_SEQUENCE ) );
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC |
+                                                           MBEDTLS_ASN1_CONSTRUCTED | 3 ) );
+    }
 
     /*
      *  SubjectPublicKeyInfo