Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030381AbcDLSJo (ORCPT ); Tue, 12 Apr 2016 14:09:44 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:49086 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966358AbcDLSIY (ORCPT ); Tue, 12 Apr 2016 14:08:24 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Vasily Kulikov , Solar Designer , Thomas Gleixner , "Kirill A. Shutemov" , Andrew Morton , Linus Torvalds , Moritz Muehlenhoff , Luis Henriques Subject: [PATCH 3.16.y-ckt 06/17] include/linux/poison.h: fix LIST_POISON{1,2} offset Date: Tue, 12 Apr 2016 19:07:53 +0100 Message-Id: <1460484484-22395-7-git-send-email-luis.henriques@canonical.com> In-Reply-To: <1460484484-22395-1-git-send-email-luis.henriques@canonical.com> References: <1460484484-22395-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2120 Lines: 50 3.16.7-ckt27 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Vasily Kulikov commit 8a5e5e02fc83aaf67053ab53b359af08c6c49aaf upstream. Poison pointer values should be small enough to find a room in non-mmap'able/hardly-mmap'able space. E.g. on x86 "poison pointer space" is located starting from 0x0. Given unprivileged users cannot mmap anything below mmap_min_addr, it should be safe to use poison pointers lower than mmap_min_addr. The current poison pointer values of LIST_POISON{1,2} might be too big for mmap_min_addr values equal or less than 1 MB (common case, e.g. Ubuntu uses only 0x10000). There is little point to use such a big value given the "poison pointer space" below 1 MB is not yet exhausted. Changing it to a smaller value solves the problem for small mmap_min_addr setups. The values are suggested by Solar Designer: http://www.openwall.com/lists/oss-security/2015/05/02/6 Signed-off-by: Vasily Kulikov Cc: Solar Designer Cc: Thomas Gleixner Cc: "Kirill A. Shutemov" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Moritz Muehlenhoff Signed-off-by: Luis Henriques --- include/linux/poison.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/poison.h b/include/linux/poison.h index 2110a81c5e2a..253c9b4198ef 100644 --- a/include/linux/poison.h +++ b/include/linux/poison.h @@ -19,8 +19,8 @@ * under normal circumstances, used to verify that nobody uses * non-initialized list entries. */ -#define LIST_POISON1 ((void *) 0x00100100 + POISON_POINTER_DELTA) -#define LIST_POISON2 ((void *) 0x00200200 + POISON_POINTER_DELTA) +#define LIST_POISON1 ((void *) 0x100 + POISON_POINTER_DELTA) +#define LIST_POISON2 ((void *) 0x200 + POISON_POINTER_DELTA) /********** include/linux/timer.h **********/ /*