linux-kernel - Re: [Linux Kernel Bug] UBSAN: array-index-out-of-bounds in rds_cmsg

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Message-ID: <c4cd5048-1838-4464-ba79-26cc595e380f@infradead.org>
Date: Sun, 21 Jan 2024 21:48:36 -0800
From: Randy Dunlap <rdunlap@...radead.org>
To: Zhu Yanjun <yanjun.zhu@...ux.dev>, Chenyuan Yang <chenyuan0y@...il.com>,
 santosh.shilimkar@...cle.com, netdev@...r.kernel.org,
 linux-rdma@...r.kernel.org, rds-devel@....oracle.com,
 linux-kernel@...r.kernel.org
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
 pabeni@...hat.com, "syzkaller@...glegroups.com"
 <syzkaller@...glegroups.com>, Zijie Zhao <zzjas98@...il.com>
Subject: Re: [Linux Kernel Bug] UBSAN: array-index-out-of-bounds in
 rds_cmsg_recv

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?

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
> 
> 

-- 
#Randy