--- zzzz-none-000/linux-2.6.32.61/include/net/rtnetlink.h	2013-06-10 09:43:48.000000000 +0000
+++ virian-300e-630/linux-2.6.32.61/include/net/rtnetlink.h	2010-07-16 10:24:07.000000000 +0000
@@ -16,7 +16,9 @@
 
 static inline int rtnl_msg_family(const struct nlmsghdr *nlh)
 {
-	if (nlmsg_len(nlh) >= sizeof(struct rtgenmsg))
+	int len = nlmsg_len(nlh);
+
+	if ((len >= 0) && ((unsigned int) len >= sizeof(struct rtgenmsg)))
 		return ((struct rtgenmsg *) nlmsg_data(nlh))->rtgen_family;
 	else
 		return AF_UNSPEC;