l2tp: fix info leak in l2tp_ip6_recvmsg()

[ Upstream commit b860d3cc62877fad02863e2a08efff69a19382d2 ]

The L2TP code for IPv6 fails to initialize the l2tp_conn_id member of
struct sockaddr_l2tpip6 and therefore leaks four bytes kernel stack
in l2tp_ip6_recvmsg() in case msg_name is set.

Initialize l2tp_conn_id with 0 to avoid the info leak.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index 8ee4a86ae996ca624e06a1422e4e07a2e957c584..9e1822e811367700d950f991ead479c841897b08 100644 (file)
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -684,6 +684,7 @@ static int l2tp_ip6_recvmsg(struct kiocb *iocb, struct sock *sk,
                lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
                lsa->l2tp_flowinfo = 0;
                lsa->l2tp_scope_id = 0;
+               lsa->l2tp_conn_id = 0;
                if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
                        lsa->l2tp_scope_id = IP6CB(skb)->iif;
        }