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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F6F1C433EF for ; Thu, 4 Nov 2021 07:16:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 75ABB61053 for ; Thu, 4 Nov 2021 07:16:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230410AbhKDHSv (ORCPT ); Thu, 4 Nov 2021 03:18:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:36198 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230335AbhKDHSt (ORCPT ); Thu, 4 Nov 2021 03:18:49 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6675961056; Thu, 4 Nov 2021 07:16:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1636010170; bh=/dVlynt37zb9p9c8G7o66XYxQ/Hn5PBByKWDe/nablk=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=sHPXjo7NKu63XF4cSFNT+TBoso3STuQipEnf+3hv/5siAjihVxRx2vWLG/TRLuf7U JdtQJuq/VySNcJ49MApb5HWDROOgBaw58I/4MNtPVcBEuhP/8SG3pbtWWMCSHhA5Ct eP7yN+1gM3XcQbJWrBMz/hcWfGSGyEFW8Ma1kra6P89Bg5A+EntXZ5GJ4wT8iqnQ3p D6KXLjluvAvvTkbH+mP7SlUADYD9t4//6/hvAB2YtCqN/wI7OnYRBuzVNrs63fjARS cpY3/o2K+CBBpu9u817Ht7mIqK6IOhI0cwNvTVUymc+Uut0+Di1ALCUNhQBTsh2wV1 +kcEAVbGFkhgA== Message-ID: Date: Thu, 4 Nov 2021 15:16:06 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.2.1 Subject: Re: [PATCH] fs: f2fs: fix UAF in f2fs_available_free_memory Content-Language: en-US To: Dongliang Mu , Jaegeuk Kim Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org References: <20211103142228.1235864-1-mudongliangabcd@gmail.com> From: Chao Yu In-Reply-To: <20211103142228.1235864-1-mudongliangabcd@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/11/3 22:22, Dongliang Mu wrote: > f2fs_fill_super > -> f2fs_build_segment_manager > -> create_discard_cmd_control > -> f2fs_start_discard_thread > > It invokes kthread_run to create a thread and run issue_discard_thread. > > However, if f2fs_build_node_manager fails, the control flow goes to > free_nm and calls f2fs_destroy_node_manager. This function will free > sbi->nm_info. However, if issue_discard_thread accesses sbi->nm_info > after the deallocation, but before the f2fs_stop_discard_thread, it will > cause UAF(Use-after-free). > > -> f2fs_destroy_segment_manager > -> destroy_discard_cmd_control > -> f2fs_stop_discard_thread > > Fix this by switching the order of f2fs_build_segment_manager > and f2fs_build_node_manager. > > Signed-off-by: Dongliang Mu > --- > fs/f2fs/super.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > index 78ebc306ee2b..1a23b64cfb74 100644 > --- a/fs/f2fs/super.c > +++ b/fs/f2fs/super.c > @@ -4135,18 +4135,18 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) > } > > /* setup f2fs internal modules */ > - err = f2fs_build_segment_manager(sbi); > - if (err) { > - f2fs_err(sbi, "Failed to initialize F2FS segment manager (%d)", > - err); > - goto free_sm; > - } > err = f2fs_build_node_manager(sbi); > if (err) { > f2fs_err(sbi, "Failed to initialize F2FS node manager (%d)", > err); > goto free_nm; > } > + err = f2fs_build_segment_manager(sbi); > + if (err) { > + f2fs_err(sbi, "Failed to initialize F2FS segment manager (%d)", > + err); > + goto free_sm; > + } > > /* For write statistics */ > sbi->sectors_written_start = f2fs_get_sectors_written(sbi); > @@ -4351,10 +4351,10 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) > sbi->node_inode = NULL; > free_stats: > f2fs_destroy_stats(sbi); > -free_nm: > - f2fs_destroy_node_manager(sbi); > free_sm: > f2fs_destroy_segment_manager(sbi); > +free_nm: > + f2fs_destroy_node_manager(sbi); IIRC, above two functions shouldn't not be called reversely due to some resource dependency, Jaegeuk, please help to confirm this. So I suggest to call destroy_discard_cmd_control() before f2fs_destroy_node_manager(), is it fine to you? Thanks, > f2fs_destroy_post_read_wq(sbi); > stop_ckpt_thread: > f2fs_stop_ckpt_thread(sbi); >