From mboxrd@z Thu Jan  1 00:00:00 1970
From: Igor Grinberg <grinberg@compulab.co.il>
Date: Thu, 18 Sep 2014 15:38:32 +0300
Subject: [U-Boot] A minor question on a Driver Model function
In-Reply-To: <87oauez2t4.fsf@nbsps.com>
References: <CAPnjgZ3HuRcEO5Do-zaMu1JDZ5kigyO2juWxpzX2_sy+Mn_YGw@mail.gmail.com>	<54169D84.9030400@compulab.co.il>	<20140917171856.3BCB.AA925319@jp.panasonic.com>	<54198F86.3080802@compulab.co.il>
	<87oauez2t4.fsf@nbsps.com>
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Hi Bill,

On 09/17/14 18:25, Bill Pringlemeir wrote:
> 
>> On 12 September 2014 05:25, Masahiro Yamada <yamada.m@jp.panasonic.com> wrote:
> 
>>>>>> I have a qustion about lists_driver_lookup_name() function.
> 
>>>>>> for (entry = drv; entry != drv + n_ents; entry++) {
>>>>>> if (strncmp(name, entry->name, len))
>>>>>> continue;
> 
>>>>>> /* Full match */
>>>>>> if (len == strlen(entry->name))
>>>>>> return entry;
>>>>>> }
> 
>>>> On 09/14/14 21:28, Simon Glass wrote:
> 
>>>> I would suggest still using strncmp as it is safer,
>>>> but count also the '\0', so something like:
> 
> On 17 Sep 2014, grinberg at compulab.co.il wrote:
> 
>>> Why safer?
> 
>>> Could you give me more detailed explanation?
> 
>> On 09/17/14 11:18, Masahiro Yamada wrote:
> 
>> Well, I'm not an expert in s/w security, but I'll try to explain...
> 
> [snip]
> 
>> But, again, I'm not an expert in this area, so its only a suggestion.
> 
> I thought it was fairly apparent that the current code supports passing
> a string that is *NOT* null terminated.  This can be convenient if you
> extract a sub-string from a command line and do not need to make a copy
> that is NULL terminate or perform 'strtok()' type magic.

Here is the whole function:

------------------------------cut--------------------------
struct driver *lists_driver_lookup_name(const char *name)
{
        struct driver *drv =
                ll_entry_start(struct driver, driver);
        const int n_ents = ll_entry_count(struct driver, driver);
        struct driver *entry;
        int len;

        if (!drv || !n_ents)
                return NULL;

        len = strlen(name);

        for (entry = drv; entry != drv + n_ents; entry++) {
                if (strncmp(name, entry->name, len))
                        continue;

                /* Full match */
                if (len == strlen(entry->name))
                        return entry;
        }

        /* Not found */
        return NULL;
}
------------------------------cut--------------------------

and... no, the code does not support passing a string that is
not null terminated.

-- 
Regards,
Igor.