From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (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 ED82928725C for ; Mon, 3 Nov 2025 02:35:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=140.211.166.137 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762137325; cv=none; b=fpYsOUpHeRJyXIZyFZPIQrs2VQItcnGtRw4wejSw7vccvZv1rx2l3BKdBCa3pQPU0nt4+mxEwvczRmVxTJhiSHy9mJSyzh2DY+/iZ8ycn+wTzdF71XM9DhozLI/4hARbWksVkCOFphgjXQFZvvLE2s59FwGepjLCOCq0d4aBsg0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762137325; c=relaxed/simple; bh=Po4FITX4drt+WLGHqKt44ddsd+cJ95meWgcRiywsgWI=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=ICbI6U/ofPgy7yB8+kMSbf+S9Mxcci0CP2b//JqyNkZpjhmXMtcHXt6RC16CuCPH4FSdDtv0sG6CqqYDRFK02ggxGlyarzL5rJ2PB5euxW8sFMtESsarftQIS66Bg8E7LxipSywW6dTHSY2Bq/Z8ankaltoMoXAkHcZ+eJYKNLQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DRIHBj45; arc=none smtp.client-ip=140.211.166.137 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DRIHBj45" Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 8A3674132C for ; Mon, 3 Nov 2025 02:35:23 +0000 (UTC) X-Virus-Scanned: amavis at osuosl.org X-Spam-Flag: NO X-Spam-Score: -5.792 X-Spam-Level: Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavis, port 10024) with ESMTP id IXrVX4M8g8gK for ; Mon, 3 Nov 2025 02:35:22 +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 smtp4.osuosl.org 951FF4129A Authentication-Results: smtp4.osuosl.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org DKIM-Filter: OpenDKIM Filter v2.11.0 smtp4.osuosl.org 951FF4129A Authentication-Results: smtp4.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=DRIHBj45 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by smtp4.osuosl.org (Postfix) with ESMTPS id 951FF4129A for ; Mon, 3 Nov 2025 02:35:22 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id F1AC8419E6; Mon, 3 Nov 2025 02:35:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E2C65C4CEF7; Mon, 3 Nov 2025 02:35:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762137321; bh=Po4FITX4drt+WLGHqKt44ddsd+cJ95meWgcRiywsgWI=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=DRIHBj45SABwSm7nwmUPGcarQCoImukTtihhrTOlN0GxOb5ugziEHQIBW08lK7/3e pPmKR5koEcyIlpD/luPAhyXTUhG4Gxx60kS4TnNHQrNynJ2vmc8Y6qRaWZ7GK/wGSR Tb7BkHsCqQtwne2k4McY/9c0vYiDMXvwsh6wYwulir4II4U9TlmofcKNM4x8Dzi6Uc MU38ocx8yNVBXw1YAHsvHV5eF6myK0ukRKv36E9EdF1ESD2lljE6WrWz8QK8J7Ko6b BePDcVrp/Lvo0JP/IcpcASn3LpIPFNL0VtBu5fcdaRJSDq3jiN7W/E/bcL0XfD8m8V T+g/LSC4L3AxQ== Message-ID: Date: Mon, 3 Nov 2025 10:35:17 +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, 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 v2 2/2] f2fs: Add sanity checks before unlinking and loading inodes To: "Nikola Z. Ivanov" , jaegeuk@kernel.org, linux-f2fs-devel@lists.sourceforge.net References: <55522ef8f3424e563ff18a720c709dcb065091af.1761993022.git.zlatistiv@gmail.com> Content-Language: en-US From: Chao Yu In-Reply-To: <55522ef8f3424e563ff18a720c709dcb065091af.1761993022.git.zlatistiv@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/1/25 20:56, Nikola Z. Ivanov wrote: > Add check for inode->i_nlink == 1 for directories during unlink, > as their value is decremented twice, which can trigger a warning in > drop_nlink. In such case mark the filesystem as corrupted and return > from the function call with the relevant failure return value. > > Additionally add the 2 checks for i_nlink == 0 and i_nlink == 1 in > sanity_check_inode in order to detect on-disk corruption early. > > Reported-by: syzbot+c07d47c7bc68f47b9083@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=c07d47c7bc68f47b9083 > Tested-by: syzbot+c07d47c7bc68f47b9083@syzkaller.appspotmail.com > Signed-off-by: Nikola Z. Ivanov > --- > fs/f2fs/inode.c | 10 ++++++++++ > fs/f2fs/namei.c | 15 +++++++++++---- > 2 files changed, 21 insertions(+), 4 deletions(-) > > diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c > index 8c4eafe9ffac..089cbf3646f0 100644 > --- a/fs/f2fs/inode.c > +++ b/fs/f2fs/inode.c > @@ -294,6 +294,16 @@ static bool sanity_check_inode(struct inode *inode, struct folio *node_folio) > return false; > } > > + if (unlikely(inode->i_nlink == 0)) { This is a possible case, as an orphan inode may exist in filesystem after sudden power-cut. Thanks, > + f2fs_warn(F2FS_I_SB(inode), "%s: inode (ino=%lx) has zero i_nlink", > + __func__, inode->i_ino); > + return false; > + } else if (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); > + return false; > + } > + > if (f2fs_has_extra_attr(inode)) { > if (!f2fs_sb_has_extra_attr(sbi)) { > f2fs_warn(sbi, "%s: inode (ino=%lx) is with extra_attr, but extra_attr feature is off", > diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c > index 40cf80fd9d9a..d13077bad482 100644 > --- a/fs/f2fs/namei.c > +++ b/fs/f2fs/namei.c > @@ -572,10 +572,11 @@ 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 out; > + goto corrupted; > + } else if (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 +602,12 @@ static int f2fs_unlink(struct inode *dir, struct dentry *dentry) > > if (IS_DIRSYNC(dir)) > f2fs_sync_fs(sbi->sb, 1); > + > + goto out; > +corrupted: > + err = -EFSCORRUPTED; > + set_sbi_flag(F2FS_I_SB(inode), SBI_NEED_FSCK); > + f2fs_folio_put(folio, false); > out: > trace_f2fs_unlink_exit(inode, err); > return err;