Re: ftpd: the advisory version

[kragen () POBOX COM (Kragen Sitaker)]

Someone writes:
> [Dan Harkless wrote:]
> > len should be a size_t (which is typedef'd to be some kind of unsigned
> > int), which would avoid the problem (without having to mess with
> > explicitly unsigned chars, which will cause warnings on platforms where
> > chars are signed, for one thing).
>
> suppose domain[0] == '\x80', then if domain is `signed char' then
> len is -128, and if it's casted to unsigned int when calling
> strncpy can be 2^(sizeof(int)*8-1)-1, so there you go :)

I was going to reply to Dan's post and say the same thing, but then I
realized that he didn't mean making len size_t or otherwise unsigned
would make the code handle >127-char strings; he meant that it would
return here:

        if (len >= 64)
                return;

And he's right.  Making len be a size_t will prevent this bug from
becoming a buffer overflow.  ;)

--
<kragen () pobox com>       Kragen Sitaker     <http://www.pobox.com/~kragen/>
The Internet stock bubble didn't burst on 1999-11-08.  Hurrah!
<URL:http://www.pobox.com/~kragen/bubble.html>
The power didn't go out on 2000-01-01 either.  :)