From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Subject: Re: Detecting the availability of VSYSCALL Date: Tue, 25 Jun 2019 13:08:07 -0700 Message-ID: <201906251131.419D8ACB@keescook> References: <87v9wty9v4.fsf@oldenburg2.str.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Content-Disposition: inline In-Reply-To: <87v9wty9v4.fsf@oldenburg2.str.redhat.com> To: Florian Weimer Cc: linux-api@vger.kernel.org, kernel-hardening@lists.openwall.com, linux-x86_64@vger.kernel.org, linux-arch@vger.kernel.org, Andy Lutomirski , Carlos O'Donell List-Id: linux-arch.vger.kernel.org On Tue, Jun 25, 2019 at 05:15:27PM +0200, Florian Weimer wrote: > Should we try mapping something at the magic address (without MAP_FIXED) > and see if we get back a different address? Something in the auxiliary > vector would work for us, too, but nothing seems to exists there > unfortunately. It seems like mmap() won't even work because it's in the high memory area. I can't map something a page under the vsyscall page either, so I can't distinguish it with mmap, mprotect, madvise, or msync. :( -- Kees Cook From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f196.google.com ([209.85.215.196]:44963 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726576AbfFYUIJ (ORCPT ); Tue, 25 Jun 2019 16:08:09 -0400 Received: by mail-pg1-f196.google.com with SMTP id n2so9470413pgp.11 for ; Tue, 25 Jun 2019 13:08:09 -0700 (PDT) Date: Tue, 25 Jun 2019 13:08:07 -0700 From: Kees Cook Subject: Re: Detecting the availability of VSYSCALL Message-ID: <201906251131.419D8ACB@keescook> References: <87v9wty9v4.fsf@oldenburg2.str.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87v9wty9v4.fsf@oldenburg2.str.redhat.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Florian Weimer Cc: linux-api@vger.kernel.org, kernel-hardening@lists.openwall.com, linux-x86_64@vger.kernel.org, linux-arch@vger.kernel.org, Andy Lutomirski , Carlos O'Donell Message-ID: <20190625200807.swUScyKrNz_bJ3knW85mVbDodC07CxcCVcLFpHMebEE@z> On Tue, Jun 25, 2019 at 05:15:27PM +0200, Florian Weimer wrote: > Should we try mapping something at the magic address (without MAP_FIXED) > and see if we get back a different address? Something in the auxiliary > vector would work for us, too, but nothing seems to exists there > unfortunately. It seems like mmap() won't even work because it's in the high memory area. I can't map something a page under the vsyscall page either, so I can't distinguish it with mmap, mprotect, madvise, or msync. :( -- Kees Cook