From: ChenXiaoSong <chenxiaosong@chenxiaosong.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-cifs@vger.kernel.org, linux-kernel@vger.kernel.org,
Steve French <sfrench@samba.org>,
Paulo Alcantara <pc@manguebit.org>,
Ronnie Sahlberg <ronniesahlberg@gmail.com>,
Shyam Prasad N <sprasad@microsoft.com>,
Tom Talpey <tom@talpey.com>, Bharath SM <bharathsm@microsoft.com>,
samba-technical@lists.samba.org, stable <stable@kernel.org>
Subject: Re: [PATCH 1/2] smb: client: fix off-by-8 bounds check in check_wsl_eas()
Date: Wed, 8 Apr 2026 13:58:27 +0800 [thread overview]
Message-ID: <68bc86cc-1c57-4734-9c75-14c9de80bd71@chenxiaosong.com> (raw)
In-Reply-To: <2026040822-shortly-chump-8518@gregkh>
The for loop does not seem to catch cases where `outlen` is excessively
large. In such cases, smb2_compound_op() would use this large `outlen`
to `memcpy()`, which could lead to OOB.
```
smb2_compound_op()
{
...
size[0] = outlen; // very large
check_wsl_eas()
memcpy(..., outlen) // out-of-bounds
...
}
```
On 4/8/26 13:39, Greg Kroah-Hartman wrote:
> On Wed, Apr 08, 2026 at 10:51:12AM +0800, ChenXiaoSong wrote:
>> Sashiko reported another out-of-bounds issue:
>> https://sashiko.dev/#/patchset/2026040635-banking-unsoiled-3250@gregkh
>>
>> Should we add the following checks in check_wsl_eas()?
>>
>> ```
>> --- a/fs/smb/client/smb2inode.c
>> +++ b/fs/smb/client/smb2inode.c
>> @@ -121,6 +121,9 @@ static int check_wsl_eas(struct kvec *rsp_iov)
>> ea = (void *)((u8 *)rsp_iov->iov_base +
>> le16_to_cpu(rsp->OutputBufferOffset));
>> end = (u8 *)rsp_iov->iov_base + rsp_iov->iov_len;
>> + if (ea + outlen > end)
>> + return -EINVAL;
>
> Then you would miss any "first" structures here, as I think the for loop
> catches this later on with the line:
>
>
>> +
>> for (;;) {
>> if ((u8 *)ea > end - sizeof(*ea))
>> return -EINVAL;
>
> That one, right?
>
> Or am I misreading this?
>
> Pointer math is "fun" :(
>
> thanks,
>
> greg k-h
--
ChenXiaoSong <chenxiaosong@kylinos.cn>
Chinese Homepage: chenxiaosong.com
English Homepage: chenxiaosong.com/en
next prev parent reply other threads:[~2026-04-08 5:59 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-06 13:49 [PATCH 0/2] smb: some potential bugfixes Greg Kroah-Hartman
2026-04-06 13:49 ` [PATCH 1/2] smb: client: fix off-by-8 bounds check in check_wsl_eas() Greg Kroah-Hartman
2026-04-08 2:51 ` ChenXiaoSong
2026-04-08 5:39 ` Greg Kroah-Hartman
2026-04-08 5:58 ` ChenXiaoSong [this message]
2026-04-08 6:15 ` Greg Kroah-Hartman
2026-04-08 6:19 ` ChenXiaoSong
2026-04-08 6:40 ` Greg Kroah-Hartman
2026-04-08 6:52 ` ChenXiaoSong
2026-04-08 6:56 ` Greg Kroah-Hartman
2026-04-09 3:09 ` ChenXiaoSong
2026-04-08 9:39 ` Yuanfu Xie
2026-04-06 13:49 ` [PATCH 2/2] smb: client: fix OOB reads parsing symlink error response Greg Kroah-Hartman
2026-04-08 9:01 ` ChenXiaoSong
2026-04-07 3:03 ` [PATCH 0/2] smb: some potential bugfixes Paulo Alcantara
[not found] ` <CAH2r5mvXFzWxs70Jmg=yWddmcHs+Bpf8eiBUvyc4oOMLzdCY7w@mail.gmail.com>
2026-04-08 5:45 ` Greg Kroah-Hartman
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