From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750822AbdAaFhj (ORCPT ); Tue, 31 Jan 2017 00:37:39 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:59906 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750727AbdAaFhf (ORCPT ); Tue, 31 Jan 2017 00:37:35 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vlastimil Babka , "Kirill A. Shutemov" , Michal Hocko , David Rientjes , "Aneesh Kumar K.V" , Andrea Arcangeli , Andrew Morton , Linus Torvalds Subject: [PATCH 4.9 13/66] mm/mempolicy.c: do not put mempolicy before using its nodemask Date: Tue, 31 Jan 2017 06:36:17 +0100 Message-Id: <20170131053603.687721181@linuxfoundation.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170131053603.098140622@linuxfoundation.org> References: <20170131053603.098140622@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 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vlastimil Babka commit d51e9894d27492783fc6d1b489070b4ba66ce969 upstream. Since commit be97a41b291e ("mm/mempolicy.c: merge alloc_hugepage_vma to alloc_pages_vma") alloc_pages_vma() can potentially free a mempolicy by mpol_cond_put() before accessing the embedded nodemask by __alloc_pages_nodemask(). The commit log says it's so "we can use a single exit path within the function" but that's clearly wrong. We can still do that when doing mpol_cond_put() after the allocation attempt. Make sure the mempolicy is not freed prematurely, otherwise __alloc_pages_nodemask() can end up using a bogus nodemask, which could lead e.g. to premature OOM. Fixes: be97a41b291e ("mm/mempolicy.c: merge alloc_hugepage_vma to alloc_pages_vma") Link: http://lkml.kernel.org/r/20170118141124.8345-1-vbabka@suse.cz Signed-off-by: Vlastimil Babka Acked-by: Kirill A. Shutemov Acked-by: Michal Hocko Acked-by: David Rientjes Cc: Aneesh Kumar K.V Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/mempolicy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2023,8 +2023,8 @@ retry_cpuset: nmask = policy_nodemask(gfp, pol); zl = policy_zonelist(gfp, pol, node); - mpol_cond_put(pol); page = __alloc_pages_nodemask(gfp, order, zl, nmask); + mpol_cond_put(pol); out: if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie))) goto retry_cpuset;