netdev - Re: net/rds: use-after-free in inet

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Date:   Tue, 28 Feb 2017 10:37:37 -0500
From:   Sowmini Varadhan <sowmini.varadhan@...cle.com>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     santosh.shilimkar@...cle.com, David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>, linux-rdma@...r.kernel.org,
        rds-devel@....oracle.com, LKML <linux-kernel@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Re: net/rds: use-after-free in inet_create

On (02/28/17 15:22), Dmitry Vyukov wrote:
> 
> Hello,
> 
> I've got the following report while running syzkaller fuzzer on
> linux-next/8d01c069486aca75b8f6018a759215b0ed0c91f0. So far it
> happened only once. net was somehow deleted from underneath
> inet_create. I've noticed that rds uses sock_create_kern which does
> not take net reference. What is that that must keep net alive then?

The rds_connection (which is where the net pointer is being obtained from)
should keep the connection alive. Did you have the rds[_tcp] modules
loaded at the time of failure? Were there kernel tcp sockets to/from
the 16385 port? any hints on what else the test was doing (was it
running a userspace RDS application that triggered the kernel TCP
connection attempt in the first place)?

--Sowmini