[PATCH] ubifs: replace simple_strtoul() with kstrtoul()

[Geert Uytterhoeven]

On Tue, May 20, 2014 at 8:53 AM, Geert Uytterhoeven
<geert at linux-m68k.org> wrote:
> On Mon, May 19, 2014 at 11:49 AM, Zhang Zhen <zhenzhang.zhang at huawei.com> wrote:
>> On 2014/5/19 17:13, Geert Uytterhoeven wrote:
>>> Please don't add mindless casts!
>>>
>>> On Mon, May 19, 2014 at 5:26 AM, Zhang Zhen <zhenzhang.zhang at huawei.com> wrote:
>>>> --- a/fs/ubifs/super.c
>>>> +++ b/fs/ubifs/super.c
>>>> @@ -1905,6 +1905,7 @@ static struct ubi_volume_desc *open_ubi(const char *name, int mode)
>>>>         struct ubi_volume_desc *ubi;
>>>>         int dev, vol;
>>>
>>> dev is int
>>>
>>>>         char *endptr;
>>>> +       int ret;
>>>>
>>>>         /* First, try to open using the device node path method */
>>>>         ubi = ubi_open_volume_path(name, mode);
>>>> @@ -1922,7 +1923,10 @@ static struct ubi_volume_desc *open_ubi(const char *name, int mode)
>>>>         if (!isdigit(name[3]))
>>>>                 return ERR_PTR(-EINVAL);
>>>>
>>>> -       dev = simple_strtoul(name + 3, &endptr, 0);
>>>> +       endptr = (char *)name + 3;
>>>> +       ret = kstrtoul(endptr, 0, (unsigned long *)&dev);
>>>
>>> On 64-bit, long is 64-bit, hence this will write beyond dev 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.
>
> That's not a cast, but an implicit conversion (which may truncate the
> value from 64-bit to 32-bit).
>
>> Or do you have any better suggestion about this?
>
> Change dev and vol to long?

Oh, there exists a whole range of kstrto*() functions.

So you can just use kstrtoint().

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at 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