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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 5DDD5C54FCB for ; Mon, 20 Apr 2020 12:47:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3DB082078E for ; Mon, 20 Apr 2020 12:47:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587386869; bh=MvXeFa5FcNNRthXLPyxuyxLB4bd5gGS+Nh1stta1QhY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=v1gQwP4elJzIop62XFLB/Dzo7DjbA+t4Rh7jnR4VMFjNDcfGVvIMIHiydfPgKQ85e 2TlLY0Fna0tT7HmdYg5CcymCrH2O9fVQwQwIRxw7fw9KyZdjE0qTCED2a8jPmAdKjf oo+XMXDVYiYXJucWY738vDX64ZolkaA+AwoSg4BI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728579AbgDTMrs (ORCPT ); Mon, 20 Apr 2020 08:47:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:43828 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729119AbgDTMrl (ORCPT ); Mon, 20 Apr 2020 08:47:41 -0400 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 016E52072B; Mon, 20 Apr 2020 12:47:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587386860; bh=MvXeFa5FcNNRthXLPyxuyxLB4bd5gGS+Nh1stta1QhY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OwTw5BeEv4v1lzMcsmESz6QxVBgX6pp2feIRpHAjhgprd5khXFSKFkO9eq/FRu4mf pCl1L8p5s3ojQ2sRlScqp05BPFoV5GiR+Dbnzvvbtge7IpXYIPgYAt55ne+TymuT5e zErvAfl1OvWWxlY5uRODOIMCT7RPEsR7GJnPEjWo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sai Praneeth Prakhya , Reinette Chatre , Borislav Petkov Subject: [PATCH 5.4 57/60] x86/resctrl: Fix invalid attempt at removing the default resource group Date: Mon, 20 Apr 2020 14:39:35 +0200 Message-Id: <20200420121515.663594031@linuxfoundation.org> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20200420121500.490651540@linuxfoundation.org> References: <20200420121500.490651540@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: Reinette Chatre commit b0151da52a6d4f3951ea24c083e7a95977621436 upstream. The default resource group ("rdtgroup_default") is associated with the root of the resctrl filesystem and should never be removed. New resource groups can be created as subdirectories of the resctrl filesystem and they can be removed from user space. There exists a safeguard in the directory removal code (rdtgroup_rmdir()) that ensures that only subdirectories can be removed by testing that the directory to be removed has to be a child of the root directory. A possible deadlock was recently fixed with 334b0f4e9b1b ("x86/resctrl: Fix a deadlock due to inaccurate reference"). This fix involved associating the private data of the "mon_groups" and "mon_data" directories to the resource group to which they belong instead of NULL as before. A consequence of this change was that the original safeguard code preventing removal of "mon_groups" and "mon_data" found in the root directory failed resulting in attempts to remove the default resource group that ends in a BUG: kernel BUG at mm/slub.c:3969! invalid opcode: 0000 [#1] SMP PTI Call Trace: rdtgroup_rmdir+0x16b/0x2c0 kernfs_iop_rmdir+0x5c/0x90 vfs_rmdir+0x7a/0x160 do_rmdir+0x17d/0x1e0 do_syscall_64+0x55/0x1d0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fix this by improving the directory removal safeguard to ensure that subdirectories of the resctrl root directory can only be removed if they are a child of the resctrl filesystem's root _and_ not associated with the default resource group. Fixes: 334b0f4e9b1b ("x86/resctrl: Fix a deadlock due to inaccurate reference") Reported-by: Sai Praneeth Prakhya Signed-off-by: Reinette Chatre Signed-off-by: Borislav Petkov Tested-by: Sai Praneeth Prakhya Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/884cbe1773496b5dbec1b6bd11bb50cffa83603d.1584461853.git.reinette.chatre@intel.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/resctrl/rdtgroup.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -3006,7 +3006,8 @@ static int rdtgroup_rmdir(struct kernfs_ * If the rdtgroup is a mon group and parent directory * is a valid "mon_groups" directory, remove the mon group. */ - if (rdtgrp->type == RDTCTRL_GROUP && parent_kn == rdtgroup_default.kn) { + if (rdtgrp->type == RDTCTRL_GROUP && parent_kn == rdtgroup_default.kn && + rdtgrp != &rdtgroup_default) { if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP || rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) { ret = rdtgroup_ctrl_remove(kn, rdtgrp);