From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932396Ab2HQS1j (ORCPT ); Fri, 17 Aug 2012 14:27:39 -0400 Received: from mail.windriver.com ([147.11.1.11]:43738 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932303Ab2HQS1Q (ORCPT ); Fri, 17 Aug 2012 14:27:16 -0400 Message-ID: <502E8CC7.4070401@windriver.com> Date: Fri, 17 Aug 2012 14:26:15 -0400 From: Paul Gortmaker User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120714 Thunderbird/14.0 MIME-Version: 1.0 To: Herton Ronaldo Krzesinski CC: , , Mitsuo Hayasaka , Andrew Morton , David Rientjes , Namhyung Kim , "Paul E. McKenney" , Jeremy Fitzhardinge , Linus Torvalds , Mel Gorman , Luciano Chavez , Rik van Riel , Willy Tarreau Subject: Re: [v2.6.34-stable 134/165] mm: avoid null pointer access in vm_struct via /proc/vmallocinfo References: <1345060109-9187-1-git-send-email-paul.gortmaker@windriver.com> <1345060109-9187-135-git-send-email-paul.gortmaker@windriver.com> <20120817152233.GB4039@herton-Z68MA-D2H-B3> In-Reply-To: <20120817152233.GB4039@herton-Z68MA-D2H-B3> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [128.224.146.65] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12-08-17 11:22 AM, Herton Ronaldo Krzesinski wrote: > On Wed, Aug 15, 2012 at 03:47:58PM -0400, Paul Gortmaker wrote: >> From: Mitsuo Hayasaka >> >> ------------------- >> 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 f5252e009d5b87071a919221e4f6624184005368 upstream. >> >> The /proc/vmallocinfo shows information about vmalloc allocations in >> vmlist that is a linklist of vm_struct. It, however, may access pages >> field of vm_struct where a page was not allocated. This results in a null >> pointer access and leads to a kernel panic. >> >> Why this happens: In __vmalloc_node_range() called from vmalloc(), newly >> allocated vm_struct is added to vmlist at __get_vm_area_node() and then, >> some fields of vm_struct such as nr_pages and pages are set at >> __vmalloc_area_node(). In other words, it is added to vmlist before it is >> fully initialized. At the same time, when the /proc/vmallocinfo is read, >> it accesses the pages field of vm_struct according to the nr_pages field >> at show_numa_info(). Thus, a null pointer access happens. >> >> The patch adds the newly allocated vm_struct to the vmlist *after* it is >> fully initialized. So, it can avoid accessing the pages field with >> unallocated page when show_numa_info() is called. >> >> Signed-off-by: Mitsuo Hayasaka >> Cc: Andrew Morton >> Cc: David Rientjes >> Cc: Namhyung Kim >> Cc: "Paul E. McKenney" >> Cc: Jeremy Fitzhardinge >> Signed-off-by: Andrew Morton >> Signed-off-by: Linus Torvalds >> [PG: .34 has VMALLOC_START/END vs. start/end in f5252e009d5] >> Signed-off-by: Paul Gortmaker > [...] > > commit 1368edf0647ac112d8cfa6ce47257dc950c50f5c ("mm: vmalloc: check for > page allocation failure before vmlist insertion") addresses a regression > on this change, something to consider for inclusion in this stable > update as well. Thanks Herton. I've added Willy to CC, since v2.6.32.49 added f5252e but does not have 1368edf0 yet in any 2.6.32.x Paul. -- >