[PATCH] Improve DST handling (Bug 23102, Bug 21942, Bug 18018, Bug, 23259, CVE-2011-0536 ).

[Florian Weimer]

On 06/06/2018 07:10 PM, Carlos O'Donell wrote:
> On 06/06/2018 12:30 PM, Andreas Schwab wrote:
>> On Jun 06 2018, Carlos O'Donell <carlos@redhat.com> wrote:
>>
>>> +  /* Find longest valid input sequence.  */
>>> +  ilen = 0;
>>> +  while ((input[ilen] >= 'A' && input[ilen] <= 'Z')
>>> +	 || (input[ilen] >= 'a' && input[ilen] <= 'z')
>>> +	 || (input[ilen] >= '0' && input[ilen] <= '9')
>>> +	 || (input[ilen] == '_'))
>>> +    ++ilen;
>>> +
>>> +  rlen = strlen (ref);
>>> +
>>> +  /* Can't be the DST we are looking for.  */
>>> +  if (rlen != ilen)
>>> +    return 0;
>>
>> Why do you need that?  Just compare, then check the next character.
> 
> Are you suggesting that:
> ~~~
> rlen = strlen (ref);
> 
> /* Can't be the DST we are looking for.  */
> if (rlen != ilen)
>    return 0;
> ~~~
> Can be dropped because we are going to compare the strings anyway?
> 
> I can do that.

If you compare the lengths first, yo ucan use memcmp.

You could compute the length of ref in an inline wrapper function, so 
that GCC will turn it into a compile-time constant.

Thanks,
Florian