Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753516AbdHVTO5 (ORCPT ); Tue, 22 Aug 2017 15:14:57 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:44650 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752692AbdHVTOx (ORCPT ); Tue, 22 Aug 2017 15:14:53 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Oleg Nesterov , Thomas Gleixner , "Kirill A. Shutemov" , Cyrill Gorcunov , Dmitry Safonov , Andy Lutomirski , Andrew Morton , Borislav Petkov , Linus Torvalds Subject: [PATCH 4.12 30/41] x86: Fix norandmaps/ADDR_NO_RANDOMIZE Date: Tue, 22 Aug 2017 12:13:58 -0700 Message-Id: <20170822190943.141235361@linuxfoundation.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170822190941.918296529@linuxfoundation.org> References: <20170822190941.918296529@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1832 Lines: 55 4.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Oleg Nesterov commit 47ac5484fd961420e5ec0bb5b972fde381f57365 upstream. 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(). Fixes: 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()") Signed-off-by: Oleg Nesterov Signed-off-by: Thomas Gleixner Acked-by: Kirill A. Shutemov Acked-by: Cyrill Gorcunov Reviewed-by: Dmitry Safonov Cc: Andy Lutomirski Cc: Andrew Morton Cc: Borislav Petkov Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20170815153952.GA1076@redhat.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/mm/mmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -82,13 +82,13 @@ 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); }