[NETFILTER]: Fix small information leak in SO_ORIGINAL_DST (CVE-2006-1343)

It appears that sockaddr_in.sin_zero is not zeroed during
getsockopt(...SO_ORIGINAL_DST...) operation. This can lead
to an information leak (CVE-2006-1343).
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/netfilter/ip_conntrack_core.c

@@ -1318,6 +1318,7 @@ getorigdst(struct sock *sk, int optval, void __user *user, int *len)
 			.tuple.dst.u.tcp.port;
 		sin.sin_addr.s_addr = ct->tuplehash[IP_CT_DIR_ORIGINAL]
 			.tuple.dst.ip;
+		memset(sin.sin_zero, 0, sizeof(sin.sin_zero));
 
 		DEBUGP("SO_ORIGINAL_DST: %u.%u.%u.%u %u\n",
 		       NIPQUAD(sin.sin_addr.s_addr), ntohs(sin.sin_port));

net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c

@@ -348,6 +348,7 @@ getorigdst(struct sock *sk, int optval, void __user *user, int *len)
 			.tuple.dst.u.tcp.port;
 		sin.sin_addr.s_addr = ct->tuplehash[IP_CT_DIR_ORIGINAL]
 			.tuple.dst.u3.ip;
+		memset(sin.sin_zero, 0, sizeof(sin.sin_zero));
 
 		DEBUGP("SO_ORIGINAL_DST: %u.%u.%u.%u %u\n",
 		       NIPQUAD(sin.sin_addr.s_addr), ntohs(sin.sin_port));