From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from szxga03-in.huawei.com ([119.145.14.66])
 by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux))
 id 1WmKDf-0003tw-01
 for linux-mtd@lists.infradead.org; Mon, 19 May 2014 09:50:56 +0000
Message-ID: <5379D3A1.8050703@huawei.com>
Date: Mon, 19 May 2014 17:49:21 +0800
From: Zhang Zhen <zhenzhang.zhang@huawei.com>
MIME-Version: 1.0
To: Geert Uytterhoeven <geert@linux-m68k.org>
Subject: Re: [PATCH] ubifs: replace simple_strtoul() with kstrtoul()
References: <1400469756-18212-1-git-send-email-zhenzhang.zhang@huawei.com>
 <537979E9.3060209@huawei.com>
 <CAMuHMdXoJKgzfyo6OcLz1SaTO_zCuvwM8iu-cNt6msvVSRCFKA@mail.gmail.com>
In-Reply-To: <CAMuHMdXoJKgzfyo6OcLz1SaTO_zCuvwM8iu-cNt6msvVSRCFKA@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Cc: MTD Maling List <linux-mtd@lists.infradead.org>, adrian.hunter@intel.com,
 Artem Bityutskiy <dedekind1@gmail.com>
List-Id: Linux MTD discussion mailing list <linux-mtd.lists.infradead.org>
List-Unsubscribe: <http://lists.infradead.org/mailman/options/linux-mtd>,
 <mailto:linux-mtd-request@lists.infradead.org?subject=unsubscribe>
List-Archive: <http://lists.infradead.org/pipermail/linux-mtd/>
List-Post: <mailto:linux-mtd@lists.infradead.org>
List-Help: <mailto:linux-mtd-request@lists.infradead.org?subject=help>
List-Subscribe: <http://lists.infradead.org/mailman/listinfo/linux-mtd>,
 <mailto:linux-mtd-request@lists.infradead.org?subject=subscribe>

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@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.

Or do you have any better suggestion about this?
Thanks.

>> +       if (ret)
>> +               return ERR_PTR(-EINVAL);
>>
>>         /* ubiY method */
>>         if (*endptr == '\0')
> 
> 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
> 
>