linux-kernel - Re: [PATCH] lib/kstrtox.c clean kstrtoll function

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Message-ID: <CA+HOOsiP-uLJPJzn=24XiodaK89-y7Fy8oj+ALnbw4iHdtGR5A@mail.gmail.com>
Date:	Fri, 23 Jan 2015 18:55:36 +0530
From:	Anshul Garg <aksgarg1989@...il.com>
To:	Jeff Epler <jepler@...ythonic.net>
Cc:	akpm@...ux-foundation.org, Levente Kurusa <levex@...ux.com>,
	Felipe Contreras <felipe.contreras@...il.com>,
	linux-kernel@...r.kernel.org,
	"anshul.g@...sung.com" <anshul.g@...sung.com>
Subject: Re: [PATCH] lib/kstrtox.c clean kstrtoll function

Dear Mr. Jeff,

Thanks for the comments.

Yes i think overflow check logic is wrong.

So i think we can change the overflow logic -

>From --

if ((long long)tmp < 0)
+ return -ERANGE;

to -

if (((long long)tmp < LLONG_MIN) || ((long long)tmp > LLONG_MAX) )
+ return -ERANGE;

Please give your views on this change..
If this change seems correct i will update overflow logic
in my sent patch.


Hope to hear from you soon.

Thanks
Anshul Garg


On Thu, Jan 22, 2015 at 10:55 PM, Jeff Epler <jepler@...ythonic.net> wrote:
> On Thu, Jan 22, 2015 at 05:54:10AM -0800, Anshul Garg wrote:
>> -             if ((long long)(-tmp) >= 0)
>> -                     return -ERANGE;
>> -             *res = -tmp;
> ...
>> +     if ((long long)tmp < 0)
>> +             return -ERANGE;
>> +     *res = sign * tmp;
>
> I don't believe overflow handling is correct anymore with this patch.
> Did you try with the input as the most negative possible unsigned long?
>
> Jeff
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