From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756181Ab2HOTs5 (ORCPT ); Wed, 15 Aug 2012 15:48:57 -0400 Received: from mail.windriver.com ([147.11.1.11]:36292 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756120Ab2HOTss (ORCPT ); Wed, 15 Aug 2012 15:48:48 -0400 From: Paul Gortmaker To: , CC: Linus Torvalds , Paul Gortmaker Subject: [v2.6.34-stable 004/165] vm: fix vm_pgoff wrap in stack expansion Date: Wed, 15 Aug 2012 15:45:48 -0400 Message-ID: <1345060109-9187-5-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.7.12.rc2 In-Reply-To: <1345060109-9187-1-git-send-email-paul.gortmaker@windriver.com> References: <1345060109-9187-1-git-send-email-paul.gortmaker@windriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Linus Torvalds ------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. ------------------- commit a626ca6a656450e9f4df91d0dda238fff23285f4 upstream. Commit 982134ba6261 ("mm: avoid wrapping vm_pgoff in mremap()") fixed the case of a expanding mapping causing vm_pgoff wrapping when you used mremap. But there was another case where we expand mappings hiding in plain sight: the automatic stack expansion. This fixes that case too. This one also found by Robert Święcki, using his nasty system call fuzzer tool. Good job. Reported-and-tested-by: Robert Święcki Signed-off-by: Linus Torvalds [PG: .34 doesn't have perf call via 3af9e859 (in .36); adjust accordingly] Signed-off-by: Paul Gortmaker --- mm/mmap.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index b42b469..fe9b76a 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1784,10 +1784,13 @@ static int expand_downwards(struct vm_area_struct *vma, size = vma->vm_end - address; grow = (vma->vm_start - address) >> PAGE_SHIFT; - error = acct_stack_growth(vma, size, grow); - if (!error) { - vma->vm_start = address; - vma->vm_pgoff -= grow; + error = -ENOMEM; + if (grow <= vma->vm_pgoff) { + error = acct_stack_growth(vma, size, grow); + if (!error) { + vma->vm_start = address; + vma->vm_pgoff -= grow; + } } } anon_vma_unlock(vma); -- 1.7.12.rc2