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=-8.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 637F0CA9ECF for ; Fri, 1 Nov 2019 16:28:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3538E20656 for ; Fri, 1 Nov 2019 16:28:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ai3N6Ic4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728763AbfKAQ2g (ORCPT ); Fri, 1 Nov 2019 12:28:36 -0400 Received: from mail-ua1-f65.google.com ([209.85.222.65]:33810 "EHLO mail-ua1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726701AbfKAQ2f (ORCPT ); Fri, 1 Nov 2019 12:28:35 -0400 Received: by mail-ua1-f65.google.com with SMTP id q16so3093806uao.1 for ; Fri, 01 Nov 2019 09:28:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=cugJW9F3kTAr1l84/vLpT5yr86XijpMcBnCXxXWK4UA=; b=ai3N6Ic4RRGuSAsXlls5IzMaslA5Wbr/HVntf4UgHRgBb1znSgpSqTQDhgWkXAk5oM H0TMkU5NqeJqmaviuucs+F/wv2mYGbxw4p/TlWjmTA7nxtnYoIewy1UZepA7s1zvqFi+ J0gxVuzM5VGToU0Rd8Mze3tyCLh7RZ7qRdkeI4u+x2bACiJuZjdPOS6PF5wclT402Cyl E4V47Z+G3JNyTOeTMcNM9nltwL7iNcdGY46YKNmZkjxzRh51T0x1vup1917ckL2zPFgG WhafP3q/o/Aolmq4VvLO1/E0Za4fVCa/z+d1jFfQQJXZNS7+zE2mjM1J0A4RaF2Z5bp3 En0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=cugJW9F3kTAr1l84/vLpT5yr86XijpMcBnCXxXWK4UA=; b=R0SPez6SqALJIX5Kho1egOJ8evo2hDwV5ApaPn9jm+g2o//vgPCl6/8WKul4M0xW+R 6SpdBxh6vy25XKIfuCibjsXhSX2O+/ZDYiW1cyn4cYwzH9sCMpMpZrTYsPi41/abr+FN vRICmcqGuFAEN5m/oOcdZOnzdSZNG/mvMuxnjiV5TtmUI4R/4M/fMAlPatP6mkpJyo6l Lz5GB62ISlL4msudC8O7MOsEjMzDVDihy7adoRVlxtiVv8KMp6OY7IwQSIvuvqoW8txP /JDEgQp1bnTXHGy0sMDXvQo2gusQspAPJBCne8PopoB5+VuQzwcu01KUgOoHjtTEiH+Z 2AMQ== X-Gm-Message-State: APjAAAVDIluvrwKLsZN/nCpdrsaspvfgT+PWUa7rwg2kyv+Tbu4eVQzy DPPMNf8GlYth7ukX7iH9CO7eXp4eUORnopIATPtfFg== X-Google-Smtp-Source: APXvYqz0PMfInUZYTnVA7QuGr/acGPXLqC8RP/nrNkyeFglf9nt3ZmPDMS4W5mUNYn60Yk/KFVXZFpuxRp6NFZg7Kqc= X-Received: by 2002:ab0:2381:: with SMTP id b1mr5975220uan.106.1572625713398; Fri, 01 Nov 2019 09:28:33 -0700 (PDT) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191031164637.48901-1-samitolvanen@google.com> <20191031164637.48901-6-samitolvanen@google.com> <201910312050.C538F8F3@keescook> In-Reply-To: <201910312050.C538F8F3@keescook> From: Sami Tolvanen Date: Fri, 1 Nov 2019 09:28:21 -0700 Message-ID: Subject: Re: [PATCH v3 05/17] add support for Clang's Shadow Call Stack (SCS) To: Kees Cook Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Dave Martin , Laura Abbott , Mark Rutland , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux , Kernel Hardening , linux-arm-kernel , LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 31, 2019 at 8:51 PM Kees Cook wrote: > > +/* A random number to mark the end of the shadow stack. */ > > +#define SCS_END_MAGIC 0xaf0194819b1635f6UL > > Is 0xaf.... non-canonical for arm64? While "random", it should also > likely be an "impossible" value to find on the call stack. Agreed, and yes, this is non-canonical for arm64 and AFAIK all 64-bit architectures the kernel supports. I'll add a note about it. Sami