Re: [PATCH] ubi: replace simple_strtoul() with kstrtoul()

Geert Uytterhoeven
2014-05-20T06:57:48Z

On Tue, May 20, 2014 at 3:18 AM, Zhang Zhen <zhenzhang.zhang@huawei.com> wrote:
> On 2014/5/19 17:14, Geert Uytterhoeven wrote:
>> Please don't add mindless casts!
>>
>> On Mon, May 19, 2014 at 10:38 AM, Zhang Zhen <zhenzhang.zhang@huawei.com> wrote:
>>> --- a/drivers/mtd/ubi/build.c
>>> +++ b/drivers/mtd/ubi/build.c
>>> @@ -1190,10 +1190,13 @@ static struct mtd_info * __init open_mtd_by_chdev(const char *mtd_dev)
>>> static struct mtd_info * __init open_mtd_device(const char *mtd_dev)
>>> {
>>> struct mtd_info *mtd;
>>> - int mtd_num;
>>> + int mtd_num, ret;
>>> char *endp;
>>>
>>> - mtd_num = simple_strtoul(mtd_dev, &endp, 0);
>>> + endp = (char *)mtd_dev;
>>> + ret = kstrtoul(endp, 0, (unsigned long *)&mtd_num);
>>
>> On 64-bit, long is 64-bit, hence this will write beyond mtd_num and will corrupt
>> the stack.
>
> Yeah, you are right. This really may write beyond dev.
>
> The kstrtoul(const char *s, unsigned int base, unsigned long *res) only accept unsigned long
> pointer as the third parameter.
> And the original function simple_strtoul() returns unsigned long type value.
> It is also cast. So this may not corrupt the stack.
>
> Or do you have any better suggestion about this?

kstrtoint().

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds