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Message-ID: <9f7eb287-543f-4865-90ca-b853e04ff126@linux.dev>
Date: Mon, 22 Jan 2024 16:49:07 +0800
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Subject: Re: [Linux Kernel Bug] UBSAN: array-index-out-of-bounds in
 rds_cmsg_recv
To: Randy Dunlap <rdunlap@infradead.org>, Chenyuan Yang
 <chenyuan0y@gmail.com>, santosh.shilimkar@oracle.com,
 netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
 rds-devel@oss.oracle.com, linux-kernel@vger.kernel.org
Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
 pabeni@redhat.com, "syzkaller@googlegroups.com"
 <syzkaller@googlegroups.com>, Zijie Zhao <zzjas98@gmail.com>
References: <CALGdzuoVdq-wtQ4Az9iottBqC5cv9ZhcE5q8N7LfYFvkRsOVcw@mail.gmail.com>
 <27319d3d-61dd-41e3-be6c-ccc08b9b3688@linux.dev>
 <c4cd5048-1838-4464-ba79-26cc595e380f@infradead.org>
From: Zhu Yanjun <yanjun.zhu@linux.dev>
In-Reply-To: <c4cd5048-1838-4464-ba79-26cc595e380f@infradead.org>
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在 2024/1/22 13:48, Randy Dunlap 写道:
> Hi,
> 
> 
> On 1/21/24 00:34, Zhu Yanjun wrote:
>> 在 2024/1/19 22:29, Chenyuan Yang 写道:
>>> Dear Linux Kernel Developers for Network RDS,
>>>
>>> We encountered "UBSAN: array-index-out-of-bounds in rds_cmsg_recv"
>>> when testing the RDS with our generated specifications. The C
>>> reproduce program and logs for this crash are attached.
>>>
>>> This crash happens when RDS receives messages by using
>>> `rds_cmsg_recv`, which reads the `j+1` index of the array
>>> `inc->i_rx_lat_trace`
>>> (https://elixir.bootlin.com/linux/v6.7/source/net/rds/recv.c#L585).
>>> The length of `inc->i_rx_lat_trace` array is 4 (defined by
>>> `RDS_RX_MAX_TRACES`,
>>> https://elixir.bootlin.com/linux/v6.7/source/net/rds/rds.h#L289) while
>>> `j` is the value stored in another array `rs->rs_rx_trace`
>>> (https://elixir.bootlin.com/linux/v6.7/source/net/rds/recv.c#L583),
>>> which is sent from others and could be arbitrary value.
>>
>> I recommend to use the latest rds to make tests. The rds in linux kernel upstream is too old. The rds in oracle linux is newer.
> 
> Why is the upstream kernel lagging behind?  Is the RDS maintainer going
> to submit patches to update mainline?

When I was in Oracle and worked with RDS, I have planned to upgrade 
kernel rds to the latest. But after I submitted several patch series, 
Oracle Developing Center of China was shutdown. I can not finish the 
plan. But the UEK kernel in Oracle linux has the latest RDS.

If you want to make tests with rds, I recommend to use UEK kernel in 
Oracle Linux.

Or you can install UEK kernel in RedHat. IMO, this UEK kernel can also 
work in RedHat Linux.

Zhu Yanjun

> 
> Thanks.
> 
>> Zhu Yanjun
>>
>>>
>>> This crash might be exploited to read the value out-of-bound from the
>>> array by setting arbitrary values for the array `rs->rs_rx_trace`.
>>>
>>> If you have any questions or require more information, please feel
>>> free to contact us.
>>>
>>> Best,
>>> Chenyuan
>>
>>
>