From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753048AbdHOPj6 (ORCPT ); Tue, 15 Aug 2017 11:39:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50720 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752796AbdHOPj4 (ORCPT ); Tue, 15 Aug 2017 11:39:56 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com CF4B9C0546E0 Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=oleg@redhat.com Date: Tue, 15 Aug 2017 17:39:52 +0200 From: Oleg Nesterov To: Andrew Morton Cc: Andy Lutomirski , Borislav Petkov , Dmitry Safonov , "H. Peter Anvin" , Ingo Molnar , "Kirill A. Shutemov" , Linus Torvalds , Thomas Gleixner , linux-kernel@vger.kernel.org, x86@kernel.org, stable@vger.kernel.org Subject: [PATCH v2 1/2] x86: fix norandmaps/ADDR_NO_RANDOMIZE Message-ID: <20170815153952.GA1076@redhat.com> References: <20170815153932.GA1073@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170815153932.GA1073@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Tue, 15 Aug 2017 15:39:56 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Documentation/admin-guide/kernel-parameters.txt says: norandmaps Don't use address space randomization. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space but it doesn't work because arch_rnd() which is used to randomize mm->mmap_base returns a random value unconditionally. And as Kirill pointed out, ADDR_NO_RANDOMIZE is broken by the same reason. Just shift the PF_RANDOMIZE check from arch_mmap_rnd() to arch_rnd(). Signed-off-by: Oleg Nesterov Reviewed-by: Dmitry Safonov Acked-by: Kirill A. Shutemov Acked-by: Cyrill Gorcunov Fixes: 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()") Cc: stable [4.12+] --- arch/x86/mm/mmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c index 229d04a..c94df12 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -79,13 +79,13 @@ static int mmap_is_legacy(void) static unsigned long arch_rnd(unsigned int rndbits) { + if (!(current->flags & PF_RANDOMIZE)) + return 0; return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT; } unsigned long arch_mmap_rnd(void) { - if (!(current->flags & PF_RANDOMIZE)) - return 0; return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits); } -- 2.5.0