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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EA21DC4321E for ; Thu, 6 Oct 2022 17:25:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231624AbiJFRZK (ORCPT ); Thu, 6 Oct 2022 13:25:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231670AbiJFRYo (ORCPT ); Thu, 6 Oct 2022 13:24:44 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5B044B4B2; Thu, 6 Oct 2022 10:24:39 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 036F361A32; Thu, 6 Oct 2022 17:24:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0BDFBC43141; Thu, 6 Oct 2022 17:24:36 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="Y5qiz5qr" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1665077071; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hw+hnIMvKUNp0lwyCAgNJh72KYkKEhg87FRQTBs88Es=; b=Y5qiz5qraL1Ht5AhJT0KSwXJpIKonST+eqGUAuMAr8WPLDUsliL74+EorKkFA7SYfrCfCm 8cGVCfHsj2cwWwcbYEhgFOCggukYu1AfE/Xd55KyZqkCt7dB3prgYsEIRtYu+PSN2tbUgt nH/6kusiZse/I7yhTs18YFSTmdsmMIE= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 968caf85 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Thu, 6 Oct 2022 17:24:31 +0000 (UTC) Received: by mail-ua1-f50.google.com with SMTP id z14so865098uam.10; Thu, 06 Oct 2022 10:24:29 -0700 (PDT) X-Gm-Message-State: ACrzQf2CQk7P2+X6vYRNb0A8CTj0AutlJGrG+F+Km0J6dHkwI4isv0PS JKEVLkIefYWmy8DjtI3HVwmcL010PGiaNFgLyt0= X-Google-Smtp-Source: AMsMyM5KG2gwBNORWG5lbntrblDeF/IiEaNCtjq1xHSusLtpHfgrAAJFtzxp/82W985F9k39J/OxSFTwH+6dW+Mrfqw= X-Received: by 2002:ab0:6cb0:0:b0:3d7:1184:847f with SMTP id j16-20020ab06cb0000000b003d71184847fmr777504uaa.49.1665077067240; Thu, 06 Oct 2022 10:24:27 -0700 (PDT) MIME-Version: 1.0 References: <20221006165346.73159-1-Jason@zx2c4.com> <20221006165346.73159-4-Jason@zx2c4.com> <848ed24c-13ef-6c38-fd13-639b33809194@csgroup.eu> In-Reply-To: <848ed24c-13ef-6c38-fd13-639b33809194@csgroup.eu> From: "Jason A. Donenfeld" Date: Thu, 6 Oct 2022 11:24:16 -0600 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v3 3/5] treewide: use get_random_u32() when possible To: Christophe Leroy Cc: "linux-kernel@vger.kernel.org" , "patches@lists.linux.dev" , Andreas Noever , Andrew Morton , Andy Shevchenko , Borislav Petkov , Catalin Marinas , =?UTF-8?Q?Christoph_B=C3=B6hmwalder?= , Christoph Hellwig , Daniel Borkmann , Dave Airlie , Dave Hansen , "David S . Miller" , Eric Dumazet , Florian Westphal , Greg Kroah-Hartman , "H . Peter Anvin" , Heiko Carstens , Helge Deller , Herbert Xu , Huacai Chen , Hugh Dickins , Jakub Kicinski , "James E . J . Bottomley" , Jan Kara , Jason Gunthorpe , Jens Axboe , Johannes Berg , Jonathan Corbet , Jozsef Kadlecsik , KP Singh , Kees Cook , Marco Elver , Mauro Carvalho Chehab , Michael Ellerman , Pablo Neira Ayuso , Paolo Abeni , Peter Zijlstra , Richard Weinberger , Russell King , "Theodore Ts'o" , Thomas Bogendoerfer , Thomas Gleixner , Thomas Graf , Ulf Hansson , Vignesh Raghavendra , WANG Xuerui , Will Deacon , Yury Norov , "dri-devel@lists.freedesktop.org" , "kasan-dev@googlegroups.com" , "kernel-janitors@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-block@vger.kernel.org" , "linux-crypto@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-media@vger.kernel.org" , "linux-mips@vger.kernel.org" , "linux-mm@kvack.org" , "linux-mmc@vger.kernel.org" , "linux-mtd@lists.infradead.org" , "linux-nvme@lists.infradead.org" , "linux-parisc@vger.kernel.org" , "linux-rdma@vger.kernel.org" , "linux-s390@vger.kernel.org" , "linux-um@lists.infradead.org" , "linux-usb@vger.kernel.org" , "linux-wireless@vger.kernel.org" , "linuxppc-dev@lists.ozlabs.org" , "loongarch@lists.linux.dev" , "netdev@vger.kernel.org" , "sparclinux@vger.kernel.org" , "x86@kernel.org" , =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= , Chuck Lever , Jan Kara Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org Hi Christophe, On Thu, Oct 6, 2022 at 11:21 AM Christophe Leroy wrote: > Le 06/10/2022 =C3=A0 18:53, Jason A. Donenfeld a =C3=A9crit : > > The prandom_u32() function has been a deprecated inline wrapper around > > get_random_u32() for several releases now, and compiles down to the > > exact same code. Replace the deprecated wrapper with a direct call to > > the real function. The same also applies to get_random_int(), which is > > just a wrapper around get_random_u32(). > > > > Reviewed-by: Kees Cook > > Acked-by: Toke H=C3=B8iland-J=C3=B8rgensen # for sch_cak= e > > Acked-by: Chuck Lever # for nfsd > > Reviewed-by: Jan Kara # for ext4 > > Signed-off-by: Jason A. Donenfeld > > --- > > > diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/proces= s.c > > index 0fbda89cd1bb..9c4c15afbbe8 100644 > > --- a/arch/powerpc/kernel/process.c > > +++ b/arch/powerpc/kernel/process.c > > @@ -2308,6 +2308,6 @@ void notrace __ppc64_runlatch_off(void) > > unsigned long arch_align_stack(unsigned long sp) > > { > > if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_s= pace) > > - sp -=3D get_random_int() & ~PAGE_MASK; > > + sp -=3D get_random_u32() & ~PAGE_MASK; > > return sp & ~0xf; > > Isn't that a candidate for prandom_u32_max() ? > > Note that sp is deemed to be 16 bytes aligned at all time. Yes, probably. It seemed non-trivial to think about, so I didn't. But let's see here... maybe it's not too bad: If PAGE_MASK is always ~(PAGE_SIZE-1), then ~PAGE_MASK is (PAGE_SIZE-1), so prandom_u32_max(PAGE_SIZE) should yield the same thing? Is that accurate? And holds across platforms (this comes up a few places)? If so, I'll do that for a v4. Jason