Re: gethostbyname buffer overflow (glibc)

[Rich Felker <dalias@libc.org>]

On Tue, Jan 27, 2015 at 05:59:36PM +0100, Daniel Cegiełka wrote:
> eg from:
> 
> http://www.openwall.com/lists/oss-security/2015/01/27/9
> 
> # gcc ghost.c && ./a.out
> should not happen
> 
> 
>   retval = gethostbyname_r(name, &resbuf, temp.buffer,
> sizeof(temp.buffer), &result, &herrno);
> 
>   if (strcmp(temp.canary, CANARY) != 0) {
>     puts("vulnerable");
>     exit(EXIT_SUCCESS);
>   }
>   if (retval == ERANGE) {
>     puts("not vulnerable");
>     exit(EXIT_SUCCESS);
>   }
>   puts("should not happen");
>   exit(EXIT_FAILURE);
> 
> Double exit. Is something wrong with gethostbyname_r() in musl?

I'm not sure what you mean by "double exit". As far as I can tell,
musl just detects errors in a different order, and returns ENOENT (2)
rather than ERANGE because the name is not valid.

Rich