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l2tp: fix info leak in l2tp_ip6_recvmsg()

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 <>
Signed-off-by: David S. Miller <>
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commit b860d3cc62877fad02863e2a08efff69a19382d2 1 parent a5598bd
@minipli minipli authored davem330 committed
Showing with 1 addition and 0 deletions.
  1. +1 −0  net/l2tp/l2tp_ip6.c
1  net/l2tp/l2tp_ip6.c
@@ -690,6 +690,7 @@ 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;
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