From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Dichtel Subject: Re: Useless debug warning "netlink: 16 bytes leftover after parsing attributes" Date: Wed, 19 Oct 2016 17:50:50 +0200 Message-ID: <04216bf5-84a7-b6ea-57ff-9cb29a706510@6wind.com> References: <0756CFFC-5BF7-4685-A1E2-0D88B2898454@holtmann.org> Reply-To: nicolas.dichtel@6wind.com Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Cc: Michal Schmidt To: Marcel Holtmann , Network Development Return-path: Received: from mail-lf0-f50.google.com ([209.85.215.50]:33382 "EHLO mail-lf0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S945799AbcJSPu4 (ORCPT ); Wed, 19 Oct 2016 11:50:56 -0400 Received: by mail-lf0-f50.google.com with SMTP id x79so32477808lff.0 for ; Wed, 19 Oct 2016 08:50:54 -0700 (PDT) In-Reply-To: <0756CFFC-5BF7-4685-A1E2-0D88B2898454@holtmann.org> Sender: netdev-owner@vger.kernel.org List-ID: Le 18/10/2016 à 07:06, Marcel Holtmann a écrit : > Hi, > > so lately I am seeing a bunch of these warnings: > > netlink: 16 bytes leftover after parsing attributes.. > > While they give you the process name, they are still useless to track down the message that causes them. I find them even more useless since an updated userspace on an older kernel can trigger the nla_policy warning here. And that updated userspace program is doing nothing wrong by including extra attributes. So what purpose is this warning serving? Usually, it means that a netlink message is malformed, for example that the header of the family has the wrong size. An unknown attribute should not trigger this kind of message. Here is an example: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=e5eca6d41f53d Regards, Nicolas