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Message-ID: <27319d3d-61dd-41e3-be6c-ccc08b9b3688@linux.dev>
Date: Sun, 21 Jan 2024 16:34:58 +0800
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Subject: Re: [Linux Kernel Bug] UBSAN: array-index-out-of-bounds in
 rds_cmsg_recv
To: 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>
From: Zhu Yanjun <yanjun.zhu@linux.dev>
In-Reply-To: <CALGdzuoVdq-wtQ4Az9iottBqC5cv9ZhcE5q8N7LfYFvkRsOVcw@mail.gmail.com>
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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.

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