From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) (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 A91ED79CF for ; Tue, 2 Dec 2025 01:25:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.130 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764638723; cv=none; b=bBlwLV1COV+bWZ0FuuQMSgSLhaG2VrstabsB0TqOVFq7n8cBjx0x+vt78QjuehQXLbIAcfVShGdnhyle+xX8nQjDIwaG+FYRmU2bQqFZABSk5lhoR80uFF00e4wZsDSWmg724ZJLa5xt/76VrfeD6eQYmwURpuIn61UJR5TRoQk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764638723; c=relaxed/simple; bh=uHs2oPKQ3cM1cZpVBEIdmre1LDvvbJ6UGyYrPoXHXwI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Tw7bzC9elDLZ1qUAk4a+iPaYl0feo39pLzyipjF1UHF7s+9CiTbv3claU0/qcWtuMFPSe8g86/u/pbIUDZN/J4jrxc+7aPt0z9lL6Cqe4DLDEef2Nykjfm+IkGiDOnB0klv3AkZPCh7VP9rgBZZEoqhtav0SxcGCtv4aNhrElfk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=DeRz1iE/; arc=none smtp.client-ip=115.124.30.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="DeRz1iE/" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1764638716; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=vWL6sHrOHn0D74zxtiLPBX/mjidfedzAlss60GVI7FE=; b=DeRz1iE/GN84FkzXrSs6r5c79zFjMpXYCgVfoWkdgN59aQHoDW1FXiYjlZbu+FIjKqqr4cJL/9HxWoVH0bxZbf5A+H/LDqH+92MHj15lVtKdgNgJ/cI3FdKARHxK5KBi+7ClbKv04hMMMJNhlBuIYZUe4c5NEE2fumtwO0Vkap8= Received: from 30.221.128.146(mailfrom:joseph.qi@linux.alibaba.com fp:SMTPD_---0WtuB3xP_1764638715 cluster:ay36) by smtp.aliyun-inc.com; Tue, 02 Dec 2025 09:25:15 +0800 Message-ID: <971dd5c8-970d-47d0-8cd3-b2b56aa0aee8@linux.alibaba.com> Date: Tue, 2 Dec 2025 09:25:14 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] ocfs2: Invalidate inode if i_mode is zero after block read To: Heming Zhao , Ahmet Eray Karadag Cc: mark@fasheh.com, jlbec@evilplan.org, ocfs2-devel@lists.linux.dev, linux-kernel@vger.kernel.org, david.hunter.linux@gmail.com, skhan@linuxfoundation.org, syzbot+55c40ae8a0e5f3659f2b@syzkaller.appspotmail.com, Albin Babu Varghese References: <20251108120133.37443-3-eraykrdg1@gmail.com> <20251119221723.171746-2-eraykrdg1@gmail.com> From: Joseph Qi In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2025/11/20 10:32, Heming Zhao wrote: > On Thu, Nov 20, 2025 at 01:17:24AM +0300, Ahmet Eray Karadag wrote: >> A panic occurs in ocfs2_unlink due to WARN_ON(inode->i_nlink == 0) when >> handling a corrupted inode with i_mode=0 and i_nlink=0 in memory. >> >> This "zombie" inode is created because ocfs2_read_locked_inode proceeds >> even after ocfs2_validate_inode_block successfully validates a block >> that structurally looks okay (passes checksum, signature etc.) but >> contains semantically invalid data (specifically i_mode=0). The current >> validation function doesn't check for i_mode being zero. >> >> This results in an in-memory inode with i_mode=0 being added to the VFS >> cache, which later triggers the panic during unlink. >> >> Prevent this by adding an explicit check for (i_mode == 0, i_nlink == 0, non-orphan) >> within ocfs2_validate_inode_block. If the check is true, return -EFSCORRUPTED to signal >> corruption. This causes the caller (ocfs2_read_locked_inode) to invoke >> make_bad_inode(), correctly preventing the zombie inode from entering >> the cache. >> >> Reported-by: syzbot+55c40ae8a0e5f3659f2b@syzkaller.appspotmail.com >> Fixes: https://syzkaller.appspot.com/bug?extid=55c40ae8a0e5f3659f2b >> Co-developed-by: Albin Babu Varghese >> Signed-off-by: Albin Babu Varghese >> Signed-off-by: Ahmet Eray Karadag >> Previous link: https://lore.kernel.org/all/20251022222752.46758-2-eraykrdg1@gmail.com/T/ >> --- >> v2: >> - Only checking either i_links_count == 0 or i_mode == 0 >> - Not performing le16_to_cpu() anymore >> - Tested with ocfs2-test >> --- >> v3: >> - Add checking both high and low bits of i_links_count >> --- >> fs/ocfs2/inode.c | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c >> index 14bf440ea4df..c8b129db756e 100644 >> --- a/fs/ocfs2/inode.c >> +++ b/fs/ocfs2/inode.c >> @@ -1456,6 +1456,13 @@ int ocfs2_validate_inode_block(struct super_block *sb, >> goto bail; >> } >> >> + if (!ocfs2_read_links_count(di) || !di->i_mode) { > > the code logic looks good to me, but I prefer the following code to save a few > cpu cycles. > > ``` > /* only check if the "link count" or i_mode is ZERO */ > if (!(di->i_links_count | di->i_links_count_hi) || !di->i_mode) > ``` > > @Joseph > which do you like? > Sorry to miss this thread discuss. The above check looks wried since "(di->i_links_count|di->i_links_count_hi)" is meaningless, though it may work well... So I'd prefer the code readability first. BTW, from the syzbot report, I haven't seen where to show i_mode=0 or i_nlink=0. Am I missing something? Thanks, Joseph