Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753560AbbDPHzD (ORCPT ); Thu, 16 Apr 2015 03:55:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44290 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750810AbbDPHyx (ORCPT ); Thu, 16 Apr 2015 03:54:53 -0400 Date: Thu, 16 Apr 2015 09:54:50 +0200 From: Miroslav Lichvar To: One Thousand Gnomes Cc: linux-kernel@vger.kernel.org, John Stultz , Thomas Gleixner , Prarit Bhargava , Richard Cochran , Arnd Bergmann Subject: Re: [RFC][PATCH] timekeeping: Limit system time to prevent 32-bit time_t overflow Message-ID: <20150416075450.GY32271@localhost> References: <1429112488-12574-1-git-send-email-mlichvar@redhat.com> <20150415223154.65c8d05e@lxorguk.ukuu.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150415223154.65c8d05e@lxorguk.ukuu.org.uk> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1185 Lines: 30 On Wed, Apr 15, 2015 at 10:31:54PM +0100, One Thousand Gnomes wrote: > On Wed, 15 Apr 2015 17:41:28 +0200 > Miroslav Lichvar wrote: > > larger value. When the maximum is reached in normal time accumulation, > > the clock will be stepped back by one week. > > Which itself is open to exploits and dirty tricks and causes bizarre > problems. Any examples? I think it shouldn't be any worse than having system clock with incorrect time and making a backward step, which is a well understood problem. > IMHO it doesn't actually improve the situation. Do you have a 32-bit system for testing? Try "date -s @2147483600", wait one minute and see if it's not worth preventing. I think the power consumption alone is worth it. If there is some widely used application/service in which the overflow triggers an infinite loop making requests to a network service, maybe it could prevent a DDoS attack. -- Miroslav Lichvar -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/