From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-98.freemail.mail.aliyun.com (out30-98.freemail.mail.aliyun.com [115.124.30.98]) (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 E537F10E4 for ; Mon, 27 May 2024 03:32:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.98 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716780743; cv=none; b=EliVaqF/0eVlX1K/NxQ6a0+Cxbx738/2IAnRR95sr5KN5qZwWTXQJrA6EZMOpSWPx+DdJJx2a1EkeS+yqmDvGQhfS6vO+1IYEyxRk6yszmwoMLDXZPP6w01El36C7FUKDfTuUby64fYgddG6zOx2de6+vrq+tVe+E//ziWHWMYA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716780743; c=relaxed/simple; bh=yn+cbqP583YJdlOLjztmyPQpFo4tMaUqPqoiqAmDuvc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=X+xwPpVU1e5gYWdwF+4OWC0PmdnaRB+Obpt71Z1Snz6BBto1REY+1j27BI2nh0RSh7n2fTArctkUiJOxwGhMvHIv96xSVu+0amcbtD1bSf2nZ8NWfsbrKzUFEmL9IGsmDqgFimDpbT0fi+4IPL1nSNSbPf1dqHBXs1ACnhdgph4= 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=ta8Umyjd; arc=none smtp.client-ip=115.124.30.98 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="ta8Umyjd" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1716780730; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=QVCxb7S4ueaSi+l2yA1OVtkoCRaQevtwGnT3fWJMfpM=; b=ta8UmyjdCK2I79omHYEw7p/ZlhifPrzmBqDdrP+4fVAnI4BYc/ZIchKYtjKEpDeYPyOuPvucNeSeUMkFVJ4XdRHtEdRiZygrDEyX1mmxruLBclRBMPIT9syUlLdvL5X663BR88z4nbh3dxfH9ttl3QZDpb2sexsqElX+nespxbk= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R821e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033022160150;MF=joseph.qi@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0W7DF54._1716780728; Received: from 30.221.129.180(mailfrom:joseph.qi@linux.alibaba.com fp:SMTPD_---0W7DF54._1716780728) by smtp.aliyun-inc.com; Mon, 27 May 2024 11:32:09 +0800 Message-ID: <3438b583-a48a-4517-99b4-8115207804a5@linux.alibaba.com> Date: Mon, 27 May 2024 11:32:08 +0800 Precedence: bulk X-Mailing-List: ocfs2-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] ocfs2: add bounds checking to ocfs2_search_dirblock() To: lei lu Cc: mark@fasheh.com, jlbec@evilplan.org, ocfs2-devel@lists.linux.dev, Greg Kroah-Hartman References: <20240526110631.10618-1-llfamsec@gmail.com> <059f5953-4f6d-4580-9bc5-685a03364987@linux.alibaba.com> Content-Language: en-US From: Joseph Qi In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 5/27/24 11:19 AM, lei lu wrote: > code in ocfs2_search_dirblock: > if (de_buf + namelen <= dlimit && > ocfs2_match(namelen, name, de)) { > > I'm not sure what "de_buf + namelen < dlimit" means. I think "de_buf + > namelen" maybe "<= dlimit", but "((struct ocfs2_dir_entry *) de_buf)->name > + namelen" maybe "> dlimit". Or maybe we should check "de->name + namelen > <= dlimit" here? > Yes, I think you are right. de->name + namelen is a more precisely check. Thanks, Joseph > lei lu 于2024年5月27日周一 11:11写道： > >>> It seems that this check can be moved to: >>> while (de_buf < dlimit - OCFS2_DIR_MEMBER_LEN) { >>> ... >>> } >> >> Right, it also work. >> >>> dlimit = de_buf + bytes; >>> So here you mean check de_len < bytes? >>> >>> Or should we check more precisely, like in ocfs2_check_dir_entry(): >>> (de - bh->b_data) + de_len > bytes - OCFS2_DIR_REC_LEN(de->name_len) >> >> "de_buf + OCFS2_DIR_MEMBER_LEN > dlimit" checks the fixed members don't >> stray beyond valid memory region, and "de_buf + de_len > dlimit" for the >> whole de. You should mean "((char *) de - bh->b_data) + de_len > dlimit" >> which is similar to "((char *) de - bh->b_data) + rlen > >> dir->i_sb->s_blocksize)" in ocfs2_check_dir_entry. But dlimit which is end >> of the de list may not reach the block end. >> >>> This is already done in ocfs2_check_dir_entry(). >> >> Right, We need to check "de_len < OCFS2_DIR_REC_LEN(de->name_len)" before >> "ocfs2_match(namelen, name, de)", because if de->name_len is too large, I >> think maybe trigger anther OOB in ocfs2_match. Or we should call >> ocfs2_check_dir_entry earlier to do a full check for de. >> >> Joseph Qi 于2024年5月27日周一 10:33写道： >> >>> >>> >>> On 5/26/24 7:06 PM, lei lu wrote: >>>> Add a check to make sure all members of the ocfs2_dir_entry >>>> don't stray beyond valid memory region. >>>> >>>> Signed-off-by: lei lu >>>> --- >>>> fs/ocfs2/dir.c | 12 +++++++++++- >>>> 1 file changed, 11 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c >>>> index d620d4c53c6f..385576d86983 100644 >>>> --- a/fs/ocfs2/dir.c >>>> +++ b/fs/ocfs2/dir.c >>>> @@ -358,6 +358,17 @@ static inline int ocfs2_search_dirblock(struct >>> buffer_head *bh, >>>> >>>> de = (struct ocfs2_dir_entry *) de_buf; >>>> >>>> + if (unlikely(de_buf + OCFS2_DIR_MEMBER_LEN > dlimit)) { >>>> + ret = -1; >>>> + goto bail; >>>> + } >>> >>> It seems that this check can be moved to: >>> while (de_buf < dlimit - OCFS2_DIR_MEMBER_LEN) { >>> ... >>> } >>> >>>> + de_len = le16_to_cpu(de->rec_len); >>>> + if (unlikely(de_buf + de_len > dlimit) || >>> >>> dlimit = de_buf + bytes; >>> So here you mean check de_len < bytes? >>> >>> Or should we check more precisely, like in ocfs2_check_dir_entry(): >>> (de - bh->b_data) + de_len > bytes - OCFS2_DIR_REC_LEN(de->name_len) >>> >>>> + unlikely(de_len < OCFS2_DIR_REC_LEN(de->name_len))) { >>> >>> This is already done in ocfs2_check_dir_entry(). >>> >>>> + ret = -1; >>>> + goto bail; >>>> + } >>>> + >>>> if (de_buf + namelen <= dlimit && >>>> ocfs2_match(namelen, name, de)) { >>>> /* found a match - just to be sure, do a full >>> check */ >>>> @@ -371,7 +382,6 @@ static inline int ocfs2_search_dirblock(struct >>> buffer_head *bh, >>>> } >>>> >>>> /* prevent looping on a bad block */ >>>> - de_len = le16_to_cpu(de->rec_len); >>>> if (de_len <= 0) { >>>> ret = -1; >>>> goto bail; >>> >> >