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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 541E9C4332B for ; Sun, 22 Mar 2020 14:57:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 23F072072D for ; Sun, 22 Mar 2020 14:57:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726897AbgCVO5w (ORCPT ); Sun, 22 Mar 2020 10:57:52 -0400 Received: from smtprelay0099.hostedemail.com ([216.40.44.99]:53152 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726470AbgCVO5v (ORCPT ); Sun, 22 Mar 2020 10:57:51 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay08.hostedemail.com (Postfix) with ESMTP id 8E4F0182CF665; Sun, 22 Mar 2020 14:57:50 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: steel34_a211d3b44761 X-Filterd-Recvd-Size: 1815 Received: from XPS-9350.home (unknown [47.151.143.254]) (Authenticated sender: joe@perches.com) by omf05.hostedemail.com (Postfix) with ESMTPA; Sun, 22 Mar 2020 14:57:49 +0000 (UTC) Message-ID: Subject: Re: [PATCH v2] f2fs: fix potential .flags overflow on 32bit architecture From: Joe Perches To: Chao Yu , jaegeuk@kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Chao Yu Date: Sun, 22 Mar 2020 07:56:01 -0700 In-Reply-To: <20200322135614.10413-1-chao@kernel.org> References: <20200322135614.10413-1-chao@kernel.org> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.34.1-2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2020-03-22 at 21:56 +0800, Chao Yu wrote: > From: Chao Yu > > 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. [] > +static inline void __set_inode_flag(struct inode *inode, int flag) > +{ > + if (!test_bit(flag % BITS_PER_LONG, > + &F2FS_I(inode)->flags[BIT_WORD(flag)])) > + set_bit(flag % BITS_PER_LONG, > + &F2FS_I(inode)->flags[BIT_WORD(flag)]); > +} I believe you don't need to do anything like this but just let test_bit and set_bit do the indexing. if (!test_bit(flg, F2FS_I(inode->flags))) set_bit(flag, F2FS_I(inode->flags)); And there already is a function called test_and_set_bit()