But where is the free ???

app/nano_shell_command.c

@@ -38,6 +38,8 @@ void wifi_scan_result_cb(void)
     station_list[i].ssid[station_list[i].ssid_len] = '\0';
     shell_printf("station %u :\nSSID : %s\n", i, (char *)station_list[i].ssid);
   }
+
+  tls_mem_free(buf);
 }
 
 int _task_list(const shell_cmd_t *pcmd, int argc, char *const argv[])