linux-kernel - Re: [PATCH 1/2] extcon: Use BIT() macro for the left-shift operation

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Message-id: <58DCCCB6.2030206@samsung.com>
Date:   Thu, 30 Mar 2017 18:15:34 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Hans de Goede <hdegoede@...hat.com>, chanwoo@...nel.org,
        MyungJoo Ham <myungjoo.ham@...sung.com>
Subject: Re: [PATCH 1/2] extcon: Use BIT() macro for the left-shift operation

On 2017년 03월 30일 17:59, Andy Shevchenko wrote:
> On Thu, Mar 30, 2017 at 11:39 AM, Chanwoo Choi <cw00.choi@...sung.com> wrote:
>> This patch just uses the BIT() macro to make the code simple.
> 
>>         for (i = 0; i < edev->max_supported; i++) {
>>                 count += sprintf(buf + count, "%s=%d\n",
>>                                 extcon_info[edev->supported_cable[i]].name,
>> -                                !!(edev->state & (1 << i)));
>> +                                !!(edev->state & BIT(i)));
>>         }
> 
> While change is okay, the above code is fragile. There is a potential
> buffer overflow.

When extcon device is registered, extcon_dev_register() check a number of
supported external connectors. The maximum number of supported connectors
is 32. There is no buffer overflow.

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics