In gst_base_src_decide_allocation_default:

        if (!gst_buffer_pool_set_config (pool, config))
          goto config_failed;
  ...

  if (pool) {
    ...
    gst_object_unref (pool);
  }

  return TRUE;

config_failed:
  config_failed:
    GST_ELEMENT_ERROR (basesrc, RESOURCE, SETTINGS,
        ("Failed to configure the buffer pool"),
        ("Configuration is most likely invalid, please report this issue."));
    return FALSE;

The pool is ref'd so it'll be leaked upon goto to config_failed.