Re: [PATCH 2.6]: IPv6: strcpy -> strlcpy

["Murray J. Root" <murrayr@brain.org>]

On Fri, Nov 28, 2003 at 05:47:24AM +0900, YOSHIFUJI Hideaki / ?$B5HF#1QL@ wrote:
> In article <20031127200041.B25015@flint.arm.linux.org.uk> (at Thu, 27 Nov 2003 20:00:41 +0000), Russell King <rmk+lkml@arm.linux.org.uk> says:
> 
> > The thing that worries me is that an incorrect strlcpy() conversion
> > gives the impression that someone has thought about buffer underruns
> > as well as overruns, and, unless someone /has/ actually thought about
> > it, there could well still be a security problem lurking there.
> 
> Hmm, what do you actually mean by "buffer underruns?"
> 
> (If I'm correct) do you suggest that we should zero-out rest of 
> destination buffer?
> 
> if so, we may want to have a function, say strlcpy0(), like this:
> 
> size_t strlcpy0(char *dst, const char *src, size_t maxlen)
> {
>   size_t len = strlcpy(dst, src, maxlen);
>   if (maxlen && len < maxlen - 1)
>     memset(dst + len + 1, 0, maxlen - len - 1);
>   return len;
> }
> 

size_t strlcpy0(char *dst, const char *src, size_t maxlen)
{
  memset(dst, 0, maxlen);
  size_t len = strlcpy(dst, src, maxlen);
  return len;
}

-- 
Murray J. Root