linux-kernel - Re: [PATCH][next] io-wq: fix unintentional integer overflow on left shift

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Message-ID: <02517010-9244-771f-d0ce-558bbebe6a63@kernel.dk>
Date:   Fri, 25 Oct 2019 07:56:00 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Colin King <colin.king@...onical.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] io-wq: fix unintentional integer overflow on left
 shift

On 10/25/19 6:54 AM, Jens Axboe wrote:
> On 10/25/19 6:43 AM, Colin King wrote:
>> From: Colin Ian King <colin.king@...onical.com>
>>
>> Shifting the integer value 1U is evaluated with type unsigned int
>> using 32-bit arithmetic and then used in an expression that expects
>> a 64-bit value, so there is potentially an integer overflow. Fix this
>> by using the BIT_ULL macro to perform the shift and avoid the overflow.
> 
> Good catch, that should indeed have been 1ULL. I'll fold in your
> fix, thanks!

BTW, this missed the same issue on the clear side of it, in
io_worker_handle_work(). I've fixed that one up the same way.

-- 
Jens Axboe