Re: [PATCH net-next] ethtool: copy reglen to userspace

[David Miller]

From: Michal Kubecek <mkubecek@xxxxxxx>
Date: Thu, 30 May 2019 10:27:22 +0200

> I believe this should be handled by ethtool_get_regs(), either by
> returning an error or by only copying data up to original regs.len
> passed by userspace. The former seems more correct but broken userspace
> software would suddenly start to fail where it "used to work". The
> latter would be closer to current behaviour but it would mean that
> broken userspace software might nerver notice there is something wrong.

I therefore think we need to meticulously fixup all of these adjustments
of regs.len before adjusting the copy call here in generic ethtool.