From patchwork Wed Jun 3 12:09:39 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 6536551 Return-Path: X-Original-To: patchwork-linux-parisc@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 7FA56C0020 for ; Wed, 3 Jun 2015 12:37:51 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 8018B20595 for ; Wed, 3 Jun 2015 12:37:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B97D20575 for ; Wed, 3 Jun 2015 12:37:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753529AbbFCMhn (ORCPT ); Wed, 3 Jun 2015 08:37:43 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58388 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756267AbbFCMVC (ORCPT ); Wed, 3 Jun 2015 08:21:02 -0400 Received: from localhost (p33062-ipbffx02marunouchi.tokyo.ocn.ne.jp [220.96.46.62]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id E9A3BB1D; Wed, 3 Jun 2015 12:21:00 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Helge Deller , linux-parisc@vger.kernel.org, James Hogan , linux-metag@vger.kernel.org Subject: [PATCH 4.0 109/148] parisc, metag: Fix crashes due to stack randomization on stack-grows-upwards architectures Date: Wed, 3 Jun 2015 21:09:39 +0900 Message-Id: <20150603114210.120664085@linuxfoundation.org> X-Mailer: git-send-email 2.4.2 In-Reply-To: <20150603114205.337615117@linuxfoundation.org> References: <20150603114205.337615117@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 4.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Helge Deller commit d045c77c1a69703143a36169c224429c48b9eecd upstream. On architectures where the stack grows upwards (CONFIG_STACK_GROWSUP=y, currently parisc and metag only) stack randomization sometimes leads to crashes when the stack ulimit is set to lower values than STACK_RND_MASK (which is 8 MB by default if not defined in arch-specific headers). The problem is, that when the stack vm_area_struct is set up in fs/exec.c, the additional space needed for the stack randomization (as defined by the value of STACK_RND_MASK) was not taken into account yet and as such, when the stack randomization code added a random offset to the stack start, the stack effectively got smaller than what the user defined via rlimit_max(RLIMIT_STACK) which then sometimes leads to out-of-stack situations and crashes. This patch fixes it by adding the maximum possible amount of memory (based on STACK_RND_MASK) which theoretically could be added by the stack randomization code to the initial stack size. That way, the user-defined stack size is always guaranteed to be at minimum what is defined via rlimit_max(RLIMIT_STACK). This bug is currently not visible on the metag architecture, because on metag STACK_RND_MASK is defined to 0 which effectively disables stack randomization. The changes to fs/exec.c are inside an "#ifdef CONFIG_STACK_GROWSUP" section, so it does not affect other platformws beside those where the stack grows upwards (parisc and metag). Signed-off-by: Helge Deller Cc: linux-parisc@vger.kernel.org Cc: James Hogan Cc: linux-metag@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- arch/parisc/include/asm/elf.h | 4 ++++ arch/parisc/kernel/sys_parisc.c | 3 +++ fs/exec.c | 3 +++ 3 files changed, 10 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html --- a/arch/parisc/include/asm/elf.h +++ b/arch/parisc/include/asm/elf.h @@ -348,6 +348,10 @@ struct pt_regs; /* forward declaration.. #define ELF_HWCAP 0 +#define STACK_RND_MASK (is_32bit_task() ? \ + 0x7ff >> (PAGE_SHIFT - 12) : \ + 0x3ffff >> (PAGE_SHIFT - 12)) + struct mm_struct; extern unsigned long arch_randomize_brk(struct mm_struct *); #define arch_randomize_brk arch_randomize_brk --- a/arch/parisc/kernel/sys_parisc.c +++ b/arch/parisc/kernel/sys_parisc.c @@ -77,6 +77,9 @@ static unsigned long mmap_upper_limit(vo if (stack_base > STACK_SIZE_MAX) stack_base = STACK_SIZE_MAX; + /* Add space for stack randomization. */ + stack_base += (STACK_RND_MASK << PAGE_SHIFT); + return PAGE_ALIGN(STACK_TOP - stack_base); } --- a/fs/exec.c +++ b/fs/exec.c @@ -659,6 +659,9 @@ int setup_arg_pages(struct linux_binprm if (stack_base > STACK_SIZE_MAX) stack_base = STACK_SIZE_MAX; + /* Add space for stack randomization. */ + stack_base += (STACK_RND_MASK << PAGE_SHIFT); + /* Make sure we didn't let the argument array grow too large. */ if (vma->vm_end - vma->vm_start > stack_base) return -ENOMEM;