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

2 messages, 2 authors, 2016-10-19 · open the first message on its own page

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

From: Marcel Holtmann <marcel@holtmann.org>
Date: 2016-10-18 05:06:53

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?

Regards

Marcel

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

From: Nicolas Dichtel <hidden>
Date: 2016-10-19 15:50:56

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
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