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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 A6A36C432C0 for ; Tue, 3 Dec 2019 22:43:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 74CF82080F for ; Tue, 3 Dec 2019 22:43:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575412983; bh=d8tFwmVImrszxwQTnGKG3yU2XKNhYmDIDK7xuuLW7LY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ASQGugDmjaAt1B+O/ZsuOHSznC3XvGqsvUHzOHz5iCtRaorh9nY/dw2pdghdx+znB eU99EJ4KnIRocqIpefywr6V55megHIUidXyoHFhZ3EUPCsWL3dEUkKMIdDIPQZi9Xe SpxS03d9OSkxgz1OZyUfXTlnsg1qlcQEV6kaL7rM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728750AbfLCWnC (ORCPT ); Tue, 3 Dec 2019 17:43:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:58122 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728727AbfLCWm4 (ORCPT ); Tue, 3 Dec 2019 17:42:56 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5E01E206EC; Tue, 3 Dec 2019 22:42:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575412975; bh=d8tFwmVImrszxwQTnGKG3yU2XKNhYmDIDK7xuuLW7LY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pDTHz9zMfNWB5Y24aFVc/Hgs4a56aS0TZ2cLeO8qqQo9prev26qlHbJ2VdAJKiQwQ Sf3j6kXKK0IlKT7hArmKnWbJBM4UZbDAVtH6/TJ021I1ZFMkFkAFmTsfLIdl9h4e/y ju+hfCB0982bEjpnz7YEIUJNUlCakU/9xi6cF9YA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xiaochen Shen , Borislav Petkov , Fenghua Yu , Tony Luck , "H. Peter Anvin" , Ingo Molnar , pei.p.jia@intel.com, Reinette Chatre , Thomas Gleixner , x86-ml , Sasha Levin Subject: [PATCH 5.3 039/135] x86/resctrl: Prevent NULL pointer dereference when reading mondata Date: Tue, 3 Dec 2019 23:34:39 +0100 Message-Id: <20191203213014.048963542@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191203213005.828543156@linuxfoundation.org> References: <20191203213005.828543156@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Xiaochen Shen [ Upstream commit 26467b0f8407cbd628fa5b7bcfd156e772004155 ] 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 Signed-off-by: Sasha Levin --- 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 efbd54cc4e696..055c8613b5317 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; -- 2.20.1