From owner-freebsd-hackers@freebsd.org Fri Mar 17 06:04:02 2017 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 7B57AD1005D for ; Fri, 17 Mar 2017 06:04:02 +0000 (UTC) (envelope-from joerg@bec.de) Received: from relay3-d.mail.gandi.net (relay3-d.mail.gandi.net [217.70.183.195]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 49DCC12F6 for ; Fri, 17 Mar 2017 06:04:01 +0000 (UTC) (envelope-from joerg@bec.de) Received: from britannica.bec.de (cl-3506.cgn-01.de.sixxs.net [IPv6:2001:4dd0:ff00:db1::2]) (Authenticated sender: joerg@bec.de) by relay3-d.mail.gandi.net (Postfix) with ESMTPSA id 413E2A80CD for ; Fri, 17 Mar 2017 07:03:57 +0100 (CET) Date: Fri, 17 Mar 2017 07:03:54 +0100 From: Joerg Sonnenberger To: freebsd-hackers@freebsd.org Subject: Re: arc4random weakness Message-ID: <20170317060354.GB9951@britannica.bec.de> Mail-Followup-To: freebsd-hackers@freebsd.org References: <20170313220639.GB65190@pyro.eu.org> <20170315130615.GC25448@pyro.eu.org> <5160183b-9778-59aa-6cf9-118014a588eb@freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5160183b-9778-59aa-6cf9-118014a588eb@freebsd.org> User-Agent: Mutt/1.7.1 (2016-10-04) X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 17 Mar 2017 06:04:02 -0000 On Wed, Mar 15, 2017 at 11:13:26PM +0300, Andrey Chernov wrote: > On 15.03.2017 16:06, Steven Chamberlain wrote: > > Also it is great to see INHERIT_ZERO was added to mmap(2)! > > It is not so great. For a program which forks very often zeroing even > one page will be slowdown. It will be better and faster to implement it > as fork syscall wrapper setting single variable, as it already done for > threaded lib. A program which forks very often is slow enough by nature. I don't think the overhead of zeroing another page is going to make a huge difference for that. Joerg