From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E50ACA9EB0 for ; Sun, 3 Nov 2019 17:13:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3BAE22084D for ; Sun, 3 Nov 2019 17:13:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727883AbfKCRMp (ORCPT ); Sun, 3 Nov 2019 12:12:45 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:35760 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727444AbfKCRMp (ORCPT ); Sun, 3 Nov 2019 12:12:45 -0500 Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1iRJQT-0003cs-DB; Sun, 03 Nov 2019 18:12:29 +0100 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id DF7451C0018; Sun, 3 Nov 2019 18:12:28 +0100 (CET) Date: Sun, 03 Nov 2019 17:12:28 -0000 From: "tip-bot2 for Xiaochen Shen" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/urgent] x86/resctrl: Prevent NULL pointer dereference when reading mondata Cc: Xiaochen Shen , Borislav Petkov , Fenghua Yu , Tony Luck , "H. Peter Anvin" , Ingo Molnar , pei.p.jia@intel.com, Reinette Chatre , Thomas Gleixner , "x86-ml" , Ingo Molnar , Borislav Petkov , linux-kernel@vger.kernel.org In-Reply-To: <1572326702-27577-1-git-send-email-xiaochen.shen@intel.com> References: <1572326702-27577-1-git-send-email-xiaochen.shen@intel.com> MIME-Version: 1.0 Message-ID: <157280114858.29376.4595330962343256563.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/urgent branch of tip: Commit-ID: 26467b0f8407cbd628fa5b7bcfd156e772004155 Gitweb: https://git.kernel.org/tip/26467b0f8407cbd628fa5b7bcfd156e772004155 Author: Xiaochen Shen AuthorDate: Tue, 29 Oct 2019 13:25:02 +08:00 Committer: Borislav Petkov CommitterDate: Sun, 03 Nov 2019 17:51:22 +01:00 x86/resctrl: Prevent NULL pointer dereference when reading mondata When a mon group is being deleted, rdtgrp->flags is set to RDT_DELETED in rdtgroup_rmdir_mon() firstly. The structure of rdtgrp will be freed until rdtgrp->waitcount is dropped to 0 in rdtgroup_kn_unlock() later. During the window of deleting a mon group, if an application calls rdtgroup_mondata_show() to read mondata under this mon group, 'rdtgrp' returned from rdtgroup_kn_lock_live() is a NULL pointer when rdtgrp->flags is RDT_DELETED. And then 'rdtgrp' is passed in this path: rdtgroup_mondata_show() --> mon_event_read() --> mon_event_count(). Thus it results in NULL pointer dereference in mon_event_count(). Check 'rdtgrp' in rdtgroup_mondata_show(), and return -ENOENT immediately when reading mondata during the window of deleting a mon group. Fixes: d89b7379015f ("x86/intel_rdt/cqm: Add mon_data") Signed-off-by: Xiaochen Shen Signed-off-by: Borislav Petkov Reviewed-by: Fenghua Yu Reviewed-by: Tony Luck Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: pei.p.jia@intel.com Cc: Reinette Chatre Cc: Thomas Gleixner Cc: x86-ml Link: https://lkml.kernel.org/r/1572326702-27577-1-git-send-email-xiaochen.shen@intel.com --- arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c index efbd54c..055c861 100644 --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c @@ -522,6 +522,10 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg) int ret = 0; rdtgrp = rdtgroup_kn_lock_live(of->kn); + if (!rdtgrp) { + ret = -ENOENT; + goto out; + } md.priv = of->kn->priv; resid = md.u.rid;