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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BAAD2C4332F for ; Thu, 6 Oct 2022 17:24:52 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 1FAAD10E84E; Thu, 6 Oct 2022 17:24:51 +0000 (UTC) X-Greylist: delayed 14008 seconds by postgrey-1.36 at gabe; Thu, 06 Oct 2022 17:24:49 UTC Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2979410E84E for ; Thu, 6 Oct 2022 17:24:49 +0000 (UTC) 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 sin.source.kernel.org (Postfix) with ESMTPS id 9CB27CE16F9 for ; Thu, 6 Oct 2022 17:24:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B20E8C433C1 for ; Thu, 6 Oct 2022 17:24:44 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="oE2wpGIb" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1665077080; 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=oE2wpGIbQRQVj0ga2y8fZokAwaY6f7W//LHz39vdA93we7YjfP+S4VVZsgZ/z9qxD/wKnY rgOmz2kzmG7Zr5oMwd1UjfwwhzSEAwNqecltCCcInlMsK7gF0WG7Xj4P/3BKgdNxZJmOiz Wo+4gCC7YmXyyZVafcZnKjSX+SQ74Mw= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 125ae146 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO) for ; Thu, 6 Oct 2022 17:24:38 +0000 (UTC) Received: by mail-yb1-f174.google.com with SMTP id 81so3008049ybf.7 for ; Thu, 06 Oct 2022 10:24:38 -0700 (PDT) X-Gm-Message-State: ACrzQf3PpQQvUEe4xJD9cqL8IGgUe0axzPFIJ7eue3k/gRpG3FCdkhCv 0M6voR7bXlxNDsdEAOX9yelZ8HjSCMR7TLTLLKU= 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "linux-wireless@vger.kernel.org" , Ulf Hansson , "x86@kernel.org" , Jan Kara , Vignesh Raghavendra , "linux-doc@vger.kernel.org" , Peter Zijlstra , Catalin Marinas , Dave Hansen , "kernel-janitors@vger.kernel.org" , KP Singh , "dri-devel@lists.freedesktop.org" , "patches@lists.linux.dev" , "linux-mm@kvack.org" , Eric Dumazet , "netdev@vger.kernel.org" , "linux-mtd@lists.infradead.org" , "H . 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Miller" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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