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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 15216C3A5A1 for ; Mon, 26 Aug 2019 02:56:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E5B8F206BB for ; Mon, 26 Aug 2019 02:56:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729372AbfHZC43 (ORCPT ); Sun, 25 Aug 2019 22:56:29 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:50970 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729360AbfHZC43 (ORCPT ); Sun, 25 Aug 2019 22:56:29 -0400 Received: from callcc.thunk.org (guestnat-104-133-0-111.corp.google.com [104.133.0.111] (may be forged)) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id x7Q2uDYi011295 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 25 Aug 2019 22:56:14 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id D3C6442049E; Sun, 25 Aug 2019 22:56:12 -0400 (EDT) Date: Sun, 25 Aug 2019 22:56:12 -0400 From: "Theodore Y. Ts'o" To: "zhangyi (F)" Cc: linux-ext4@vger.kernel.org, jack@suse.cz, adilger.kernel@dilger.ca Subject: Re: [PATCH v5] ext4: fix potential use after free in system zone via remount with noblock_validity Message-ID: <20190826025612.GB4918@mit.edu> References: <1565869639-105420-1-git-send-email-yi.zhang@huawei.com> <20190825034000.GE5163@mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190825034000.GE5163@mit.edu> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org I added a missing rcu_read_lock() to prevent a suspicious RCU warning when CONFIG_PROVE_RCU is enabled: diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c index 003dc1dc2da3..f7bc914a74df 100644 --- a/fs/ext4/block_validity.c +++ b/fs/ext4/block_validity.c @@ -330,11 +330,13 @@ void ext4_release_system_zone(struct super_block *sb) { struct ext4_system_blocks *system_blks; + rcu_read_lock(); system_blks = rcu_dereference(EXT4_SB(sb)->system_blks); rcu_assign_pointer(EXT4_SB(sb)->system_blks, NULL); if (system_blks) call_rcu(&system_blks->rcu, ext4_destroy_system_zone); + rcu_read_unlock(); } int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk, - Ted