linux-kernel - Re: [PATCH] loop: fix to a race condition due to the early registration of device

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Message-ID: <acf56d41-a135-4758-ef0b-ca2dc345d5f2@ispras.ru>
Date:   Thu, 10 Aug 2017 18:46:46 +0300
From:   Anton Volkov <avolkov@...ras.ru>
To:     Omar Sandoval <osandov@...ndov.com>
Cc:     tom.leiming@...il.com, axboe@...com, osandov@...com,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        ldv-project@...uxtesting.org, khoroshilov@...ras.ru
Subject: Re: [PATCH] loop: fix to a race condition due to the early
 registration of device

Hello, Omar.

It was a purely theoretical race that had been considered to be possible 
in real-life.

Regards,
Anton

On 09.08.2017 01:00, Omar Sandoval wrote:
> On Mon, Aug 07, 2017 at 03:37:50PM +0300, Anton Volkov wrote:
>> The early device registration made possible a race leading to allocations
>> of disks with wrong minors.
>>
>> This patch moves the device registration further down the loop_init
>> function to make the race infeasible.
>>
>> Found by Linux Driver Verification project (linuxtesting.org).
>>
>> Signed-off-by: Anton Volkov <avolkov@...ras.ru>
>> Reviewed-by: Ming Lei <ming.lei@...hat.com>
> 
> Hi, Anton,
> 
> Were you able to reproduce this issue or was it purely theoretical? If
> the former, it'd be nice if you could add a test case to blktests [1].
> 
> 1: https://github.com/osandov/blktests
> 
> Thanks!
> Omar
> 

-- Anton Volkov
Linux Verification Center, ISPRAS
web: http://linuxtesting.org
e-mail: avolkov@...ras.ru