netdev - Re: Useless debug warning "netlink: 16 bytes leftover after parsing attributes"

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Date:   Wed, 19 Oct 2016 17:50:50 +0200
From:   Nicolas Dichtel <nicolas.dichtel@...nd.com>
To:     Marcel Holtmann <marcel@...tmann.org>,
        Network Development <netdev@...r.kernel.org>
Cc:     Michal Schmidt <mschmidt@...hat.com>
Subject: Re: Useless debug warning "netlink: 16 bytes leftover after parsing
 attributes"

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