bug in 3.2.0 nmblookup

[Sam Liddicott]

Alan DeKok wrote:
> Jeremy Allison wrote:
>   
>>> --- /tmp/tmp.66554.0    Thu Jul  3 16:02:36 2008
>>> +++ source/lib/util_sock.c Thu Jul  3 16:02:00 2008
>>> @@ -366,6 +366,7 @@
>>>         struct sockaddr_in *sa = (struct sockaddr_in *)ss;
>>>         memset(ss, '\0', sizeof(*ss));
>>>         ss->ss_family = AF_INET;
>>> +       ss->ss_len = sizeof(struct sockaddr_in);
>>>         sa->sin_addr = ip;
>>>  }
>>>       
>
>   That looks like a pointer aliasing bug to me.
>
>   Newer versions of GCC are more aggressive about optimizations.  They
> may notice that the assignment "sa->sin_addr = ip" is just before the
> closing brace... and that "sa" is a local variable, which isn't used
> after that.  So... the assignment can safely be optimized away.
>   
Thats sick!
sa may be a local variable but it is a pointer. Since when did gcc think 
that local pointers only point locally?
What if a function scope pointer was initialized from an argument struct 
(for convenience) would they optimize away that last use of that pointer 
too?

function blah(struct suff* arg) {
  struct secret *secret=stuff->secret;
  // does this get opimized away as secret is going out of scope
  secret->word="shh";
}

If I'm not wrong, this must be a gcc bug.

Sam
>   Yes... I got hit by this recently.  The solution (horrible as it
> sounds) was to memcpy back and forth between "struct sockaddr_storage"
> and "struct sockaddr_in*".
>
>   Just a heads up.  If you suddenly see that the IP's are always zero,
> this is what's going on.
>
>   Alan DeKok.
>