Subject: Re: [PATCH] brd: fix overflow in __brd_direct_access
To: Mikulas Patocka <mpatocka@redhat.com>,
        Dan Williams <dan.j.williams@intel.com>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
References: <alpine.LRH.2.02.1709130909570.1354@file01.intranet.prod.int.rdu2.redhat.com>
From: Jens Axboe <axboe@kernel.dk>
Message-ID: <fb12beef-6c0e-5c13-ab95-29683243f095@kernel.dk>
Date: Wed, 13 Sep 2017 11:18:18 -0600
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.2.1
MIME-Version: 1.0
In-Reply-To: <alpine.LRH.2.02.1709130909570.1354@file01.intranet.prod.int.rdu2.redhat.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 447
Lines: 13

On 09/13/2017 07:17 AM, Mikulas Patocka wrote:
> The code in __brd_direct_access multiplies the pgoff variable by page size
> and divides it by 512. It can cause overflow on 32-bit architectures. The
> overflow happens if we create ramdisk larger than 4G and use it as a
> sparse device.
> 
> This patch replaces multiplication and division with multiplication by the
> number of sectors per page.

Thanks, applied with Dan's ack.

-- 
Jens Axboe