From patchwork Wed Oct 12 11:02:53 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Paolo Pisati X-Patchwork-Id: 119180 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from chlorine.canonical.com (chlorine.canonical.com [91.189.94.204]) by ozlabs.org (Postfix) with ESMTP id 3D8B0B6F76 for ; Wed, 12 Oct 2011 22:03:10 +1100 (EST) Received: from localhost ([127.0.0.1] helo=chlorine.canonical.com) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1RDwaQ-0008Dt-Ut; Wed, 12 Oct 2011 11:02:59 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1RDwaP-0008DI-AO for kernel-team@lists.ubuntu.com; Wed, 12 Oct 2011 11:02:57 +0000 Received: from dynamic-adsl-94-36-124-73.clienti.tiscali.it ([94.36.124.73] helo=canonical.com) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1RDwaP-0008Oh-2t for kernel-team@lists.ubuntu.com; Wed, 12 Oct 2011 11:02:57 +0000 From: Paolo Pisati To: kernel-team@lists.ubuntu.com Subject: [PATCH 1/2] vm: fix vm_pgoff wrap in stack expansion - CVE-2011-2496 Date: Wed, 12 Oct 2011 13:02:53 +0200 Message-Id: <1318417374-5540-2-git-send-email-paolo.pisati@canonical.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1318417374-5540-1-git-send-email-paolo.pisati@canonical.com> References: <1318417374-5540-1-git-send-email-paolo.pisati@canonical.com> MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.13 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kernel-team-bounces@lists.ubuntu.com Errors-To: kernel-team-bounces@lists.ubuntu.com From: Linus Torvalds vm: fix vm_pgoff wrap in stack expansion 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 Cc: stable@kernel.org Signed-off-by: Linus Torvalds CVE-2011-2496 BugLink: http://bugs.launchpad.net/bugs/869243 commit upstream a626ca6a656450e9f4df91d0dda238fff23285f4 Signed-off-by: Paolo Pisati --- mm/mmap.c | 11 +++++++---- 1 files changed, 7 insertions(+), 4 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 058c705..745191a6a 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1892,10 +1892,13 @@ 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);