From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1B8AC28DB52 for ; Mon, 13 Oct 2025 12:53:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=140.211.166.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760359994; cv=none; b=nFIvHmbmu7Xq0AORNf7YmDsMvBqdvW1KfsX4uFKi3wsjwe0Hb76O6L62suudSDNA2I+tat3+5J05vDUSBjh2X0e8WM+i8VX5AwDs5d82xNaetlvU8FZnE88TxcNGcTyQzylaTvVyMeeXLvfApG5A35uIn7SZnyNVbBTAO+J6PUo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760359994; c=relaxed/simple; bh=QrfJt2hUMOOD+gjf01fYxogMQriU6KiB9/iGzz3A5eo=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=N/0q0sDoZc3ncAzSSqAo8UFHFcDV7vVBvyr/JpepBAYgJAnkbrR/dhyXIFMyuZAywWSJRg9gey8yBVerXYk58o8JOE57mkLkWnEWwlQKvLICdaf79HpKCAeXJQEfKzouv7dViM/icIe7CyLgHdFZL4DsowCYEyMgi5NWcMGEO/M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=O5G6+SKa; arc=none smtp.client-ip=140.211.166.133 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="O5G6+SKa" Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 7E80640891 for ; Mon, 13 Oct 2025 12:53:11 +0000 (UTC) X-Virus-Scanned: amavis at osuosl.org X-Spam-Flag: NO X-Spam-Score: -5.792 X-Spam-Level: Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavis, port 10024) with ESMTP id 5rpZBXWEf5nz for ; Mon, 13 Oct 2025 12:53:10 +0000 (UTC) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=172.234.252.31; helo=sea.source.kernel.org; envelope-from=chao@kernel.org; receiver= DMARC-Filter: OpenDMARC Filter v1.4.2 smtp2.osuosl.org 89CE640059 Authentication-Results: smtp2.osuosl.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org 89CE640059 Authentication-Results: smtp2.osuosl.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=O5G6+SKa Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by smtp2.osuosl.org (Postfix) with ESMTPS id 89CE640059 for ; Mon, 13 Oct 2025 12:53:10 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 9990045312; Mon, 13 Oct 2025 12:53:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2B590C4CEE7; Mon, 13 Oct 2025 12:53:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760359989; bh=QrfJt2hUMOOD+gjf01fYxogMQriU6KiB9/iGzz3A5eo=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=O5G6+SKanFheTVhhE+NeS8tIo4vNAICs41T/v/LM0moYsBF5dCxC6lZ/k4VedORqe uDuWtvh8BxrwZuEUb4qa59egVmQcTSFIarFOMePK9ZuzZT7TbWgcC+WLDnmLB3ogHl LEFpkJ0bJ+JiwKQfaZI2lPxTAqf4I0YlANkFEMyu7vJ/aUfNjZJdkuZdv9SaEMDTwT M3a6N7Ntf/uaCeib128QNXqJwqYo/grlDmLPo70/+QujHYLi3epUIGXJc2ZRqDN4gV SygHaeJagr/v9PsqvUgV4MYUqjEjGUxUryFzO0i4qcYn2pxmAN49LdAqXcck84RIWM qzBhQqxdfI8gg== Message-ID: <9d0fef9d-4093-4a80-af3f-6dc45ffe886c@kernel.org> Date: Mon, 13 Oct 2025 20:53:04 +0800 Precedence: bulk X-Mailing-List: linux-kernel-mentees@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: chao@kernel.org, jaegeuk@kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, david.hunter.linux@gmail.com, linux-kernel-mentees@lists.linuxfoundation.org, khalid@kernel.org, syzbot+c07d47c7bc68f47b9083@syzkaller.appspotmail.com Subject: Re: [PATCH] f2fs: Perform sanity check before unlinking directory inode To: "Nikola Z. Ivanov" References: <20251003134731.470392-1-zlatistiv@gmail.com> <839306c1-5f7a-4e89-b2cf-7534d279a03c@kernel.org> Content-Language: en-US From: Chao Yu In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/13/25 05:19, Nikola Z. Ivanov wrote: > On Thu, Oct 09, 2025 at 10:54:40AM +0800, Chao Yu wrote: >> On 10/3/2025 9:47 PM, Nikola Z. Ivanov wrote: >>> Current i_nlink corruption check does not take into account >>> directory inodes which have one additional i_nlink for their "." entry. >>> >>> Add additional check and a common corruption path. >>> >>> Reported-by: syzbot+c07d47c7bc68f47b9083@syzkaller.appspotmail.com >>> Closes: https://syzkaller.appspot.com/bug?extid=c07d47c7bc68f47b9083 >>> Fixes: 81edb983b3f5 ("f2fs: add check for deleted inode") >>> Signed-off-by: Nikola Z. Ivanov >>> --- >>> fs/f2fs/namei.c | 28 ++++++++++++++++++++-------- >>> 1 file changed, 20 insertions(+), 8 deletions(-) >>> >>> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c >>> index b882771e4699..68b33e8089b0 100644 >>> --- a/fs/f2fs/namei.c >>> +++ b/fs/f2fs/namei.c >>> @@ -502,12 +502,14 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry, >>> goto out; >>> } >>> - if (inode->i_nlink == 0) { >>> + if (unlikely(inode->i_nlink == 0)) { >>> f2fs_warn(F2FS_I_SB(inode), "%s: inode (ino=%lx) has zero i_nlink", >>> __func__, inode->i_ino); >>> - err = -EFSCORRUPTED; >>> - set_sbi_flag(F2FS_I_SB(inode), SBI_NEED_FSCK); >>> - goto out_iput; >>> + goto corrupted; >>> + } else if (unlikely(S_ISDIR(inode->i_mode) && inode->i_nlink == 1)) { >>> + f2fs_warn(F2FS_I_SB(inode), "%s: directory inode (ino=%lx) has a single i_nlink", >>> + __func__, inode->i_ino); >>> + goto corrupted; >> >> Can we detect such corruption in sanity_check_inode() as well? So that if >> f2fs internal flow calls f2fs_iget() on corrupted inode, we can set SBI_NEED_FSCK >> flag and then triggering fsck repairment later. >> >> Thanks, >> >>> } >>> if (IS_ENCRYPTED(dir) && >>> @@ -533,6 +535,9 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry, >>> trace_f2fs_lookup_end(dir, !IS_ERR_OR_NULL(new) ? new : dentry, >>> ino, IS_ERR(new) ? PTR_ERR(new) : err); >>> return new; >>> +corrupted: >>> + err = -EFSCORRUPTED; >>> + set_sbi_flag(F2FS_I_SB(inode), SBI_NEED_FSCK); >>> out_iput: >>> iput(inode); >>> out: >>> @@ -572,10 +577,11 @@ static int f2fs_unlink(struct inode *dir, struct dentry *dentry) >>> if (unlikely(inode->i_nlink == 0)) { >>> f2fs_warn(F2FS_I_SB(inode), "%s: inode (ino=%lx) has zero i_nlink", >>> __func__, inode->i_ino); >>> - err = -EFSCORRUPTED; >>> - set_sbi_flag(F2FS_I_SB(inode), SBI_NEED_FSCK); >>> - f2fs_folio_put(folio, false); >>> - goto fail; >>> + goto corrupted; >>> + } else if (unlikely(S_ISDIR(inode->i_mode) && inode->i_nlink == 1)) { >>> + f2fs_warn(F2FS_I_SB(inode), "%s: directory inode (ino=%lx) has a single i_nlink", >>> + __func__, inode->i_ino); >>> + goto corrupted; >>> } >>> f2fs_balance_fs(sbi, true); >>> @@ -601,6 +607,12 @@ static int f2fs_unlink(struct inode *dir, struct dentry *dentry) >>> if (IS_DIRSYNC(dir)) >>> f2fs_sync_fs(sbi->sb, 1); >>> + >>> + goto fail; >>> +corrupted: >>> + err = -EFSCORRUPTED; >>> + set_sbi_flag(F2FS_I_SB(inode), SBI_NEED_FSCK); >>> + f2fs_folio_put(folio, false); >>> fail: >>> trace_f2fs_unlink_exit(inode, err); >>> return err; >> > > Hi Chao, > > Thank you for the suggestion. > I will add this to sanity_check_inode and remove it > from f2fs_lookup as it becomes redundant since f2fs_lookup > obtains the inode through f2fs_iget. For f2fs_unlink I will > move the i_nlink == 1 check to f2fs_rmdir. Hi Nikola, I meant we can move the i_nlink == 1 check from both f2fs_lookup() and f2fs_unlink() to sanity_check_inode(), because before we create in-memory inode, we will always call sanity_check_inode(). Let me know if you have other concerns. Thanks, > > I will send v2 as soon as I do some more testing.