Original patch from: gentoo/src/patchsets/glibc/2.9/0050_all_glibc-_nss_dns_gethostbyaddr2_r-check-and-adjust-the-buffer-alignment.patch

-= BEGIN original header =-
http://sourceware.org/ml/libc-alpha/2009-01/msg00000.html

From 8ad7030880eaa18dcabf8e284e79026301fd3fa4 Mon Sep 17 00:00:00 2001
From: Ulrich Drepper <drepper@redhat.com>
Date: Thu, 8 Jan 2009 00:02:38 +0000
Subject: [PATCH] (_nss_dns_gethostbyaddr2_r): Check and adjust the buffer alignment.

-= END original header =-

diff -durN glibc-2_9.orig/resolv/nss_dns/dns-host.c glibc-2_9/resolv/nss_dns/dns-host.c
--- glibc-2_9.orig/resolv/nss_dns/dns-host.c	2008-11-12 08:52:20.000000000 +0100
+++ glibc-2_9/resolv/nss_dns/dns-host.c	2009-02-02 22:00:36.000000000 +0100
@@ -364,6 +364,19 @@
   int n, status;
   int olderr = errno;
 
+ uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct host_data);
+ buffer += pad;
+ buflen = buflen > pad ? buflen - pad : 0;
+
+ if (__builtin_expect (buflen < sizeof (struct host_data), 0))
+   {
+     *errnop = ERANGE;
+     *h_errnop = NETDB_INTERNAL;
+     return NSS_STATUS_TRYAGAIN;
+   }
+
+ host_data = (struct host_data *) buffer;
+
   if (__res_maybe_init (&_res, 0) == -1)
     return NSS_STATUS_UNAVAIL;