linux-kernel - Re: [PATCH] RDS: fix race condition when sending a message on unbound socket.

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Date:	Tue, 24 Nov 2015 10:43:29 -0800
From:	santosh shilimkar <santosh.shilimkar@...cle.com>
To:	Ben Hutchings <ben@...adent.org.uk>,
	Quentin Casasnovas <quentin.casasnovas@...cle.com>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	Vegard Nossum <vegard.nossum@...cle.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	Chien Yen <chien.yen@...cle.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH] RDS: fix race condition when sending a message on unbound
 socket.

On 11/24/2015 10:25 AM, Ben Hutchings wrote:
> On Tue, 2015-11-03 at 12:25 +0100, Quentin Casasnovas wrote:
>> On Fri, Oct 16, 2015 at 10:47:49AM -0700, santosh shilimkar wrote:
>>> On 10/16/2015 8:11 AM, Quentin Casasnovas wrote:
>>>> Sasha's found a NULL pointer dereference in the RDS connection code when
>>>> sending a message to an apparently unbound socket.  The problem is caused
>>>> by the code checking if the socket is bound in rds_sendmsg(), which checks
>>>> the rs_bound_addr field without taking a lock on the socket.  This opens a
>>>> race where rs_bound_addr is temporarily set but where the transport is not
>>>> in rds_bind(), leading to a NULL pointer dereference when trying to
>>>> dereference 'trans' in __rds_conn_create().
>>>>
>>>> Vegard wrote a reproducer for this issue, so kindly ask him to share if
>>>> you're interested.
>>>>
>>>> I cannot reproduce the NULL pointer dereference using Vegard's reproducer
>>>> with this patch, whereas I could without.
>>>>
>>>> Complete earlier incomplete fix to CVE-2015-6937:
>>>>
>>>>     74e98eb08588 ("RDS: verify the underlying transport exists before creating a connection")
>>>>
>>
>> For reference, this has been assigned CVE-2015-7990 on the oss-sec thread:
>>
>>    http://seclists.org/oss-sec/2015/q4/179
>
> But the patch doesn't seem to have gone anywhere.  Santosh, can you
> apply this in your tree and ask David to pull, or should Quentin re-
> send it to netdev?
>
Indeed, its not picked up yet. I will send the refreshed patch for
Dave to pull. Thanks for reporting Ben.

Regards,
Santosh
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