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l2tp: use rcu_dereference_sk_user_data() in l2tp_udp_encap_recv()

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[ Upstream commit c1c477217882c610a2ba0268f5faf36c9c092528 ]

Canonical way to fetch sk_user_data from an encap_rcv() handler called
from UDP stack in rcu protected section is to use rcu_dereference_sk_user_data(),
otherwise compiler might read it multiple times.

Fixes: d00fa9adc528 ("il2tp: fix races with tunnel socket close")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Dumazet 2019-04-23 09:43:26 -07:00 committed by Greg Kroah-Hartman
parent e571a33963
commit 485f382f2c
1 changed files with 1 additions and 1 deletions
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2
net/l2tp/l2tp_core.c
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@ -909,7 +909,7 @@ int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
{
struct l2tp_tunnel *tunnel;
tunnel = l2tp_tunnel(sk);
tunnel = rcu_dereference_sk_user_data(sk);
if (tunnel == NULL)
goto pass_up;