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Commit d694db2f authored Jul 02, 2021 by Eric Dumazet Committed by Greg Kroah-Hartman Jul 28, 2021

tcp: annotate data races around tp->mtu_info



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: 563d34d0 ("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>

parent e0355a0a

net/ipv4/tcp_ipv4.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -348,7 +348,7 @@ 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;
		@@ -516,7 +516,7 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
		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 {

net/ipv6/tcp_ipv6.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -340,7 +340,7 @@ static void tcp_v6_mtu_reduced(struct sock *sk)
		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;

		@@ -429,7 +429,7 @@ static void tcp_v6_err(struct sk_buff skb, struct inet6_skb_parm opt,
		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,