From: Eric Dumazet edumazet@google.com
commit 561022acb1ce62e50f7a8258687a21b84282a4cb upstream.
While tp->mtu_info is read while socket is owned, the write sides happen from err handlers (tcp_v[46]_mtu_reduced) which only own the socket spinlock.
Fixes: 563d34d05786 ("tcp: dont drop MTU reduction indications") Signed-off-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/tcp_ipv4.c | 4 ++-- net/ipv6/tcp_ipv6.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-)
--- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -342,7 +342,7 @@ void tcp_v4_mtu_reduced(struct sock *sk)
if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) return; - mtu = tcp_sk(sk)->mtu_info; + mtu = READ_ONCE(tcp_sk(sk)->mtu_info); dst = inet_csk_update_pmtu(sk, mtu); if (!dst) return; @@ -546,7 +546,7 @@ int tcp_v4_err(struct sk_buff *skb, u32 if (sk->sk_state == TCP_LISTEN) goto out;
- tp->mtu_info = info; + WRITE_ONCE(tp->mtu_info, info); if (!sock_owned_by_user(sk)) { tcp_v4_mtu_reduced(sk); } else { --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -352,7 +352,7 @@ static void tcp_v6_mtu_reduced(struct so if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) return;
- dst = inet6_csk_update_pmtu(sk, tcp_sk(sk)->mtu_info); + dst = inet6_csk_update_pmtu(sk, READ_ONCE(tcp_sk(sk)->mtu_info)); if (!dst) return;
@@ -443,7 +443,7 @@ static int tcp_v6_err(struct sk_buff *sk if (!ip6_sk_accept_pmtu(sk)) goto out;
- tp->mtu_info = ntohl(info); + WRITE_ONCE(tp->mtu_info, ntohl(info)); if (!sock_owned_by_user(sk)) tcp_v6_mtu_reduced(sk); else if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED,