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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 D5AB4C2D0EB for ; Sun, 29 Mar 2020 12:21:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BEC8C2073B for ; Sun, 29 Mar 2020 12:21:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BEC8C2073B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=ACULAB.COM Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 245986B0010; Sun, 29 Mar 2020 08:21:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1F6AE6B0032; Sun, 29 Mar 2020 08:21:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 10CB06B0036; Sun, 29 Mar 2020 08:21:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0126.hostedemail.com [216.40.44.126]) by kanga.kvack.org (Postfix) with ESMTP id EC20F6B0010 for ; Sun, 29 Mar 2020 08:21:51 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id CBC5A40C6 for ; Sun, 29 Mar 2020 12:21:51 +0000 (UTC) X-FDA: 76648311222.17.wall99_4a61715fb9c1d X-HE-Tag: wall99_4a61715fb9c1d X-Filterd-Recvd-Size: 2685 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [146.101.78.151]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Sun, 29 Mar 2020 12:21:50 +0000 (UTC) Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-135-E2d1cB3MNcKiBN6SYycyaw-1; Sun, 29 Mar 2020 13:21:47 +0100 X-MC-Unique: E2d1cB3MNcKiBN6SYycyaw-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Sun, 29 Mar 2020 13:21:47 +0100 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Sun, 29 Mar 2020 13:21:47 +0100 From: David Laight To: 'George Spelvin' , Dan Williams CC: Linux Kernel Mailing List , Qian Cai , Kees Cook , Michal Hocko , Andrew Morton , Linux MM Subject: RE: [RFC PATCH v1 00/52] Audit kernel random number use Thread-Topic: [RFC PATCH v1 00/52] Audit kernel random number use Thread-Index: AQHWBS7wHKwkXcotX0GE2ObBbkw++6hffddg Date: Sun, 29 Mar 2020 12:21:46 +0000 Message-ID: <98bd30f23b374ccbb61dd46125dc9669@AcuMS.aculab.com> References: <202003281643.02SGhPmY017434@sdf.org> <20200328182817.GE5859@SDF.ORG> In-Reply-To: <20200328182817.GE5859@SDF.ORG> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: George Spelvin > Sent: 28 March 2020 18:28 ... > 20..23: Changes to the prandom_u32() generator itself. Including > switching to a stronger & faster PRNG. Does this remove the code that used 'xor' to combine the output of (about) 5 LFSR? Or is that somewhere else? I didn't spot it in the patches - so it might already have gone. Using xor was particularly stupid. The whole generator was then linear and trivially reversable. Just using addition would have made it much stronger. =09David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1= PT, UK Registration No: 1397386 (Wales)