embed: hdnode field length fix

embed/extmod/modtrezorcrypto/modtrezorcrypto-bip32.h

@@ -74,21 +74,21 @@ STATIC mp_obj_t mod_trezorcrypto_HDNode_make_new(const mp_obj_type_t *type, size
     mp_get_buffer_raise(vals[5].u_obj, &public_key, MP_BUFFER_READ);
     mp_get_buffer_raise(vals[6].u_obj, &curve_name, MP_BUFFER_READ);
 
-    if (NULL == chain_code.buf || 32 != chain_code.len) {
+    if (32 != chain_code.len) {
         mp_raise_ValueError("chain_code is invalid");
     }
-    if (NULL == public_key.buf && NULL == private_key.buf) {
+    if (0 == public_key.len && 0 == private_key.len) {
         mp_raise_ValueError("either public_key or private_key is required");
     }
-    if (NULL != private_key.buf && 32 != private_key.len) {
+    if (0 != private_key.len && 32 != private_key.len) {
         mp_raise_ValueError("private_key is invalid");
     }
-    if (NULL != public_key.buf && 33 != public_key.len) {
+    if (0 != public_key.len && 33 != public_key.len) {
         mp_raise_ValueError("public_key is invalid");
     }
 
     const curve_info *curve = NULL;
-    if (NULL == curve_name.buf) {
+    if (0 == curve_name.len) {
         curve = get_curve_by_name(SECP256K1_NAME);
     } else {
         curve = get_curve_by_name(curve_name.buf);
@@ -103,17 +103,17 @@ STATIC mp_obj_t mod_trezorcrypto_HDNode_make_new(const mp_obj_type_t *type, size
     o->fingerprint = fingerprint;
     o->hdnode.depth = depth;
     o->hdnode.child_num = child_num;
-    if (NULL != chain_code.buf && 32 == chain_code.len) {
+    if (32 == chain_code.len) {
         memcpy(o->hdnode.chain_code, chain_code.buf, 32);
     } else {
         memzero(o->hdnode.chain_code, 32);
     }
-    if (NULL != private_key.buf && 32 == private_key.len) {
+    if (32 == private_key.len) {
         memcpy(o->hdnode.private_key, private_key.buf, 32);
     } else {
         memzero(o->hdnode.private_key, 32);
     }
-    if (NULL != public_key.buf && 33 == public_key.len) {
+    if (33 == public_key.len) {
         memcpy(o->hdnode.public_key, public_key.buf, 33);
     } else {
         memzero(o->hdnode.public_key, 33);