Fix problematic strcpy

YubikeyKeyDerivationLibrary/openvpn_yubikey_key_management.c

@@ -206,8 +206,9 @@ OPENVPN_EXPORT int openvpn_plugin_open_v3(const int v3structver, struct openvpn_
     // Access Code
     if (strcmp(argv[2], "0") != 0)
     {
-        context->acc_code = calloc(strlen(argv[2]) + 1, sizeof(char));
-        strcpy(context->acc_code, argv[2]);
+        unsigned long access_code_length = strlen(argv[2]) + 1;
+        context->acc_code = calloc(access_code_length, sizeof(char));
+        snprintf(context->acc_code, access_code_length, "%s", argv[2]);
         plog(PLOG_DEBUG, "Using access code %s", context->acc_code);
         if (! context->acc_code)
         {