From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xi Wang Subject: Re: [PATCH] ipv4: avoid undefined behavior in do_ip_setsockopt() Date: Mon, 12 Nov 2012 12:00:54 -0500 Message-ID: <50A12B46.4010805@gmail.com> References: <1352668801-14373-1-git-send-email-xi.wang@gmail.com><20121111.170247.780516266044882867.davem@davemloft.net><50A0244F.1070302@gmail.com> <20121111.175056.930119228369321440.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: David Miller , netdev@vger.kernel.org To: David Laight Return-path: Received: from mail-vb0-f46.google.com ([209.85.212.46]:49016 "EHLO mail-vb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751613Ab2KLRBD (ORCPT ); Mon, 12 Nov 2012 12:01:03 -0500 Received: by mail-vb0-f46.google.com with SMTP id ff1so6443850vbb.19 for ; Mon, 12 Nov 2012 09:01:02 -0800 (PST) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 11/12/12 8:54 AM, David Laight wrote: > 'All modern' is probably an overstatement, 'recent gcc' might be valid. I agree if you consider gcc 3.4 released 8 years ago as "recent gcc", or if you use a compiler other than gcc/clang/icc to compile the kernel. > The 'switch' version will have an extra conditional to detect > 'out of range' values - even though we know they can't happen. > I'm not sure you can avoid that - even for an enum. This out-of-range check is exactly what this patch wanted to add: optname is a syscall parameter, and we should reject invalid optname values before doing (1<