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 4CF20C1975A for ; Mon, 23 Mar 2020 02:19:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 26FF320774 for ; Mon, 23 Mar 2020 02:19:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727066AbgCWCTz (ORCPT ); Sun, 22 Mar 2020 22:19:55 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:57082 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726954AbgCWCTz (ORCPT ); Sun, 22 Mar 2020 22:19:55 -0400 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 725CCD8523A1F9EF112E; Mon, 23 Mar 2020 10:19:50 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.202) with Microsoft SMTP Server (TLS) id 14.3.487.0; Mon, 23 Mar 2020 10:19:44 +0800 Subject: Re: [PATCH v3] f2fs: fix potential .flags overflow on 32bit architecture To: Joe Perches , CC: , , References: <20200323012519.41536-1-yuchao0@huawei.com> From: Chao Yu Message-ID: <68bc1967-8772-d04a-1209-d919bf122f9f@huawei.com> Date: Mon, 23 Mar 2020 10:19:44 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/3/23 10:00, Joe Perches wrote: > On Mon, 2020-03-23 at 09:25 +0800, Chao Yu wrote: >> f2fs_inode_info.flags is unsigned long variable, it has 32 bits >> in 32bit architecture, since we introduced FI_MMAP_FILE flag >> when we support data compression, we may access memory cross >> the border of .flags field, corrupting .i_sem field, result in >> below deadlock. >> >> To fix this issue, let's expand .flags as an array to grab enough >> space to store new flags. > [] >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > [] >> @@ -2586,22 +2590,28 @@ static inline void __mark_inode_dirty_flag(struct inode *inode, >> } >> } >> >> +static inline void __set_inode_flag(struct inode *inode, int flag) >> +{ >> + test_and_set_bit(flag % BITS_PER_LONG, >> + &F2FS_I(inode)->flags[BIT_WORD(flag)]); > > I believe this should just use > > test_and_set_bit(flag, F2FS_I(inode)->flags); > >> static inline int is_inode_flag_set(struct inode *inode, int flag) >> { >> - return test_bit(flag, &F2FS_I(inode)->flags); >> + return test_bit(flag % BITS_PER_LONG, >> + &F2FS_I(inode)->flags[BIT_WORD(flag)]); > > here too. > > test_bit(flag, F2FS_I(inode)->flags); > >> static inline void clear_inode_flag(struct inode *inode, int flag) >> { >> - if (test_bit(flag, &F2FS_I(inode)->flags)) >> - clear_bit(flag, &F2FS_I(inode)->flags); >> + test_and_clear_bit(flag % BITS_PER_LONG, >> + &F2FS_I(inode)->flags[BIT_WORD(flag)]); > > and here. My bad, Ondřej Jirman also reminded me this issue, will fix this soon. Thanks, > > I also don't know why these functions are used at all. > > > . >