From 69925a346acb70be33059f4940ed703ffe0b0756 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Tue, 20 Jun 2023 18:24:23 +0200 Subject: mptcp: ensure listener is unhashed before updating the sk status commit 57fc0f1ceaa4016354cf6f88533e20b56190e41a upstream. The MPTCP protocol access the listener subflow in a lockless manner in a couple of places (poll, diag). That works only if the msk itself leaves the listener status only after that the subflow itself has been closed/disconnected. Otherwise we risk deadlock in diag, as reported by Christoph. Address the issue ensuring that the first subflow (the listener one) is always disconnected before updating the msk socket status. Reported-by: Christoph Paasch Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/407 Fixes: b29fcfb54cd7 ("mptcp: full disconnect implementation") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts Signed-off-by: Matthieu Baerts Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/mptcp/pm_netlink.c | 1 + net/mptcp/protocol.c | 26 ++++++++++++++++++++------ 2 files changed, 21 insertions(+), 6 deletions(-) (limited to 'net') diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 01d34ee4525e..9127a7fd5269 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -1039,6 +1039,7 @@ static int mptcp_pm_nl_create_listen_socket(struct sock *sk, return err; } + inet_sk_state_store(newsk, TCP_LISTEN); err = kernel_listen(ssock, backlog); if (err) { pr_warn("kernel_listen error, err=%d", err); diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index a2c6ce40e426..4ca61e80f4bb 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2400,12 +2400,6 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk, kfree_rcu(subflow, rcu); } else { /* otherwise tcp will dispose of the ssk and subflow ctx */ - if (ssk->sk_state == TCP_LISTEN) { - tcp_set_state(ssk, TCP_CLOSE); - mptcp_subflow_queue_clean(sk, ssk); - inet_csk_listen_stop(ssk); - } - __tcp_close(ssk, 0); /* close acquired an extra ref */ @@ -2939,6 +2933,24 @@ static __poll_t mptcp_check_readable(struct mptcp_sock *msk) return EPOLLIN | EPOLLRDNORM; } +static void mptcp_check_listen_stop(struct sock *sk) +{ + struct sock *ssk; + + if (inet_sk_state_load(sk) != TCP_LISTEN) + return; + + ssk = mptcp_sk(sk)->first; + if (WARN_ON_ONCE(!ssk || inet_sk_state_load(ssk) != TCP_LISTEN)) + return; + + lock_sock_nested(ssk, SINGLE_DEPTH_NESTING); + mptcp_subflow_queue_clean(sk, ssk); + inet_csk_listen_stop(ssk); + tcp_set_state(ssk, TCP_CLOSE); + release_sock(ssk); +} + bool __mptcp_close(struct sock *sk, long timeout) { struct mptcp_subflow_context *subflow; @@ -2949,6 +2961,7 @@ bool __mptcp_close(struct sock *sk, long timeout) WRITE_ONCE(sk->sk_shutdown, SHUTDOWN_MASK); if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) { + mptcp_check_listen_stop(sk); inet_sk_state_store(sk, TCP_CLOSE); goto cleanup; } @@ -3062,6 +3075,7 @@ static int mptcp_disconnect(struct sock *sk, int flags) if (msk->fastopening) return -EBUSY; + mptcp_check_listen_stop(sk); inet_sk_state_store(sk, TCP_CLOSE); mptcp_stop_timer(sk); -- cgit v1.2.3