From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 73FACC28CC0 for ; Thu, 30 May 2019 18:26:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 570F125F8D for ; Thu, 30 May 2019 18:26:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726748AbfE3S0d (ORCPT ); Thu, 30 May 2019 14:26:33 -0400 Received: from shards.monkeyblade.net ([23.128.96.9]:56736 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726649AbfE3S0b (ORCPT ); Thu, 30 May 2019 14:26:31 -0400 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::3d5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 19E9F14D92C59; Thu, 30 May 2019 11:26:31 -0700 (PDT) Date: Thu, 30 May 2019 11:26:30 -0700 (PDT) Message-Id: <20190530.112630.476132829981439143.davem@davemloft.net> To: mkubecek@suse.cz Cc: netdev@vger.kernel.org, vivien.didelot@gmail.com, linux-kernel@vger.kernel.org, kernel@savoirfairelinux.com, linville@redhat.com, f.fainelli@gmail.com Subject: Re: [PATCH net-next] ethtool: copy reglen to userspace From: David Miller In-Reply-To: <20190530082722.GB27401@unicorn.suse.cz> References: <20190529.221744.1136074795446305909.davem@davemloft.net> <20190530064848.GA27401@unicorn.suse.cz> <20190530082722.GB27401@unicorn.suse.cz> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 30 May 2019 11:26:31 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michal Kubecek 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.