From patchwork Mon Mar 1 16:13:16 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 389145 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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, 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 B027BC433DB for ; Mon, 1 Mar 2021 20:25:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 78B8360235 for ; Mon, 1 Mar 2021 20:25:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241293AbhCAUZG (ORCPT ); Mon, 1 Mar 2021 15:25:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:45782 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243214AbhCAUSz (ORCPT ); Mon, 1 Mar 2021 15:18:55 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4137D65319; Mon, 1 Mar 2021 18:03:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614621818; bh=7huvN+C20SkmZILgftz3wqApWdpSaE+GDlgsLyMY1P8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lTqHDf++S7tbglSsaxdcC2p8u0/DxwZRRL+cp2VF2351Jmiu0Y8wtQXwJgnh5i3KH 2K64HtkkOhK+MnfZp92Se4Pn1EvQX0LYs4AFwaFJLIV2AQyyZvD8MZ50refOw4Opi+ gJCgLaTaouMR3PVGUooX2qJ9m+6TXN8qyLnvGR9E= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Huang Jianan , Chao Yu , Gao Xiang Subject: [PATCH 5.11 628/775] erofs: initialized fields can only be observed after bit is set Date: Mon, 1 Mar 2021 17:13:16 +0100 Message-Id: <20210301161232.432812782@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210301161201.679371205@linuxfoundation.org> References: <20210301161201.679371205@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Gao Xiang commit ce063129181312f8781a047a50be439c5859747b upstream. Currently, although set_bit() & test_bit() pairs are used as a fast- path for initialized configurations. However, these atomic ops are actually relaxed forms. Instead, load-acquire & store-release form is needed to make sure uninitialized fields won't be observed in advance here (yet no such corresponding bitops so use full barriers instead.) Link: https://lore.kernel.org/r/20210209130618.15838-1-hsiangkao@aol.com Fixes: 62dc45979f3f ("staging: erofs: fix race of initializing xattrs of a inode at the same time") Fixes: 152a333a5895 ("staging: erofs: add compacted compression indexes support") Cc: # 5.3+ Reported-by: Huang Jianan Reviewed-by: Chao Yu Signed-off-by: Gao Xiang Signed-off-by: Greg Kroah-Hartman --- fs/erofs/xattr.c | 10 +++++++++- fs/erofs/zmap.c | 10 +++++++++- 2 files changed, 18 insertions(+), 2 deletions(-) --- a/fs/erofs/xattr.c +++ b/fs/erofs/xattr.c @@ -48,8 +48,14 @@ static int init_inode_xattrs(struct inod int ret = 0; /* the most case is that xattrs of this inode are initialized. */ - if (test_bit(EROFS_I_EA_INITED_BIT, &vi->flags)) + if (test_bit(EROFS_I_EA_INITED_BIT, &vi->flags)) { + /* + * paired with smp_mb() at the end of the function to ensure + * fields will only be observed after the bit is set. + */ + smp_mb(); return 0; + } if (wait_on_bit_lock(&vi->flags, EROFS_I_BL_XATTR_BIT, TASK_KILLABLE)) return -ERESTARTSYS; @@ -137,6 +143,8 @@ static int init_inode_xattrs(struct inod } xattr_iter_end(&it, atomic_map); + /* paired with smp_mb() at the beginning of the function. */ + smp_mb(); set_bit(EROFS_I_EA_INITED_BIT, &vi->flags); out_unlock: --- a/fs/erofs/zmap.c +++ b/fs/erofs/zmap.c @@ -36,8 +36,14 @@ static int z_erofs_fill_inode_lazy(struc void *kaddr; struct z_erofs_map_header *h; - if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags)) + if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags)) { + /* + * paired with smp_mb() at the end of the function to ensure + * fields will only be observed after the bit is set. + */ + smp_mb(); return 0; + } if (wait_on_bit_lock(&vi->flags, EROFS_I_BL_Z_BIT, TASK_KILLABLE)) return -ERESTARTSYS; @@ -83,6 +89,8 @@ static int z_erofs_fill_inode_lazy(struc vi->z_physical_clusterbits[1] = vi->z_logical_clusterbits + ((h->h_clusterbits >> 5) & 7); + /* paired with smp_mb() at the beginning of the function */ + smp_mb(); set_bit(EROFS_I_Z_INITED_BIT, &vi->flags); unmap_done: kunmap_atomic(kaddr);