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Subject: Re: [PATCH] RDS: Fix rds-ping inducing kernel panic
To:     Kees Cook <keescook@chromium.org>
Cc:     Honggang Li <honli@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Sowmini Varadhan <sowmini.varadhan@oracle.com>,
        Steve Beattie <sbeattie@ubuntu.com>,
        Andy Whitcroft <apw@canonical.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jay Fenlason <fenlason@redhat.com>,
        Network Development <netdev@vger.kernel.org>,
        linux-rdma <linux-rdma@vger.kernel.org>, rds-devel@oss.oracle.com
References: <20180122112415.GA41074@beast>
 <2768ae2b-b7de-cf00-c599-4c164a6228be@oracle.com>
 <CAGXu5jKhPk2MPCvYCOTbcNs7vdej5iuzJbJ9tM92QqXc7MczUA@mail.gmail.com>
From:   Santosh Shilimkar <santosh.shilimkar@oracle.com>
Organization: Oracle Corporation
Message-ID: <8cec0803-701a-be79-802d-bac2e84acbbd@oracle.com>
Date:   Mon, 22 Jan 2018 14:25:47 -0800
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On 1/22/2018 2:17 PM, Kees Cook wrote:
> On Tue, Jan 23, 2018 at 4:01 AM, Santosh Shilimkar
> <santosh.shilimkar@oracle.com> wrote:
>> On 1/22/2018 3:24 AM, Kees Cook wrote:
>>>
>>> As described in: https://bugzilla.redhat.com/show_bug.cgi?id=822754
>>>
>>> Attempting an RDS connection from the IP address of an IPoIB interface
>>> to itself causes a kernel panic due to a BUG_ON() being triggered.
>>> Making the test less strict allows rds-ping to work without crashing
>>> the machine.
>>>
>>> A local unprivileged user could use this flaw to crash the sytem.
>>>
>> Are you able to reproduce this issue on mainline kernel ?
>> IIRC, this sjouldn't happen anymore but if you see it, please
>> let me know. Will try it as well. rds-ping on self
>> loopback device is often tested and used as well for
>> monitoring services in production.
> 
> I don't have an RDS test setup, no. But it sounds like kernels without
> this patch aren't seeing the problem.
>
Yep. Thats what I thought and hence asked.

>> Am not sure if its applicable anymore. Infact the issue with
>> loopback device was due to congestion update and thats been
>> already addressed with commit '18fc25c94: {rds: prevent BUG_ON
>> triggered on congestion update to loopback}'
> 
> That looks very much like it was fixed there. Thanks!
> 
Yeah. Thanks Kees !!

Regards,
Santosh