From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934904Ab0CMAU0 (ORCPT ); Fri, 12 Mar 2010 19:20:26 -0500 Received: from kroah.org ([198.145.64.141]:60605 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934841Ab0CMATp (ORCPT ); Fri, 12 Mar 2010 19:19:45 -0500 X-Mailbox-Line: From gregkh@kvm.kroah.org Fri Mar 12 16:15:07 2010 Message-Id: <20100313001506.929414064@kvm.kroah.org> User-Agent: quilt/0.48-4.4 Date: Fri, 12 Mar 2010 16:11:58 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Thomas Gleixner , Bjorn Helgaas , Yinghai Lu , Jesse Barnes Subject: [patch 020/123] x86/PCI: Prevent mmconfig memory corruption In-Reply-To: <20100313001618.GA9811@kroah.com> In-Reply-To: <20100313001618.GA9811@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.33-stable review patch. If anyone has any objections, please let me know. ----------------- From: Thomas Gleixner commit bb8d41330ce27edb91adb6922d3f8e1a8923f727 upstream. commit ff097ddd4 (x86/PCI: MMCONFIG: manage pci_mmcfg_region as a list, not a table) introduced a nasty memory corruption when pci_mmcfg_list is empty. pci_mmcfg_check_end_bus_number() dereferences pci_mmcfg_list.prev even when the list is empty. The following write hits some variable near to pci_mmcfg_list. Further down a similar problem exists, where cfg->list.next is dereferenced unconditionally and a comparison with some variable near to pci_mmcfg_list happens. Add a check for the last element into the for_each_entry() loop and remove all the other crappy logic which is just a leftover of the old array based code which was replaced by the list conversion. Reported-by: Ingo Molnar Signed-off-by: Thomas Gleixner Cc: Bjorn Helgaas Cc: Yinghai Lu Signed-off-by: Jesse Barnes Signed-off-by: Greg Kroah-Hartman --- arch/x86/pci/mmconfig-shared.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) --- a/arch/x86/pci/mmconfig-shared.c +++ b/arch/x86/pci/mmconfig-shared.c @@ -303,22 +303,17 @@ static void __init pci_mmcfg_check_end_b { struct pci_mmcfg_region *cfg, *cfgx; - /* last one*/ - cfg = list_entry(pci_mmcfg_list.prev, typeof(*cfg), list); - if (cfg) - if (cfg->end_bus < cfg->start_bus) - cfg->end_bus = 255; - - if (list_is_singular(&pci_mmcfg_list)) - return; - - /* don't overlap please */ + /* Fixup overlaps */ list_for_each_entry(cfg, &pci_mmcfg_list, list) { if (cfg->end_bus < cfg->start_bus) cfg->end_bus = 255; + /* Don't access the list head ! */ + if (cfg->list.next == &pci_mmcfg_list) + break; + cfgx = list_entry(cfg->list.next, typeof(*cfg), list); - if (cfg != cfgx && cfg->end_bus >= cfgx->start_bus) + if (cfg->end_bus >= cfgx->start_bus) cfg->end_bus = cfgx->start_bus - 1; } }