From ebb516af60e18258aac8e80bbe068740ef1579ed Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 14 Oct 2015 11:16:28 -0700 Subject: tcp/dccp: fix race at listener dismantle phase Under stress, a close() on a listener can trigger the WARN_ON(sk->sk_ack_backlog) in inet_csk_listen_stop() We need to test if listener is still active before queueing a child in inet_csk_reqsk_queue_add() Create a common inet_child_forget() helper, and use it from inet_csk_reqsk_queue_add() and inet_csk_listen_stop() Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/inet_connection_sock.c | 71 ++++++++++++++++++++++++++++------------- 1 file changed, 49 insertions(+), 22 deletions(-) (limited to 'net/ipv4/inet_connection_sock.c') diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index b85c720956a9..8430bc8ccd58 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -764,6 +764,53 @@ int inet_csk_listen_start(struct sock *sk, int backlog) } EXPORT_SYMBOL_GPL(inet_csk_listen_start); +static void inet_child_forget(struct sock *sk, struct request_sock *req, + struct sock *child) +{ + sk->sk_prot->disconnect(child, O_NONBLOCK); + + sock_orphan(child); + + percpu_counter_inc(sk->sk_prot->orphan_count); + + if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) { + BUG_ON(tcp_sk(child)->fastopen_rsk != req); + BUG_ON(sk != req->rsk_listener); + + /* Paranoid, to prevent race condition if + * an inbound pkt destined for child is + * blocked by sock lock in tcp_v4_rcv(). + * Also to satisfy an assertion in + * tcp_v4_destroy_sock(). + */ + tcp_sk(child)->fastopen_rsk = NULL; + } + inet_csk_destroy_sock(child); + reqsk_put(req); +} + +void inet_csk_reqsk_queue_add(struct sock *sk, struct request_sock *req, + struct sock *child) +{ + struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue; + + spin_lock(&queue->rskq_lock); + if (unlikely(sk->sk_state != TCP_LISTEN)) { + inet_child_forget(sk, req, child); + } else { + req->sk = child; + req->dl_next = NULL; + if (queue->rskq_accept_head == NULL) + queue->rskq_accept_head = req; + else + queue->rskq_accept_tail->dl_next = req; + queue->rskq_accept_tail = req; + sk_acceptq_added(sk); + } + spin_unlock(&queue->rskq_lock); +} +EXPORT_SYMBOL(inet_csk_reqsk_queue_add); + /* * This routine closes sockets which have been at least partially * opened, but not yet accepted. @@ -790,31 +837,11 @@ void inet_csk_listen_stop(struct sock *sk) WARN_ON(sock_owned_by_user(child)); sock_hold(child); - sk->sk_prot->disconnect(child, O_NONBLOCK); - - sock_orphan(child); - - percpu_counter_inc(sk->sk_prot->orphan_count); - - if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) { - BUG_ON(tcp_sk(child)->fastopen_rsk != req); - BUG_ON(sk != req->rsk_listener); - - /* Paranoid, to prevent race condition if - * an inbound pkt destined for child is - * blocked by sock lock in tcp_v4_rcv(). - * Also to satisfy an assertion in - * tcp_v4_destroy_sock(). - */ - tcp_sk(child)->fastopen_rsk = NULL; - } - inet_csk_destroy_sock(child); - + inet_child_forget(sk, req, child); bh_unlock_sock(child); local_bh_enable(); sock_put(child); - reqsk_put(req); cond_resched(); } if (queue->fastopenq.rskq_rst_head) { @@ -829,7 +856,7 @@ void inet_csk_listen_stop(struct sock *sk) req = next; } } - WARN_ON(sk->sk_ack_backlog); + WARN_ON_ONCE(sk->sk_ack_backlog); } EXPORT_SYMBOL_GPL(inet_csk_listen_stop); -- cgit v1.2.3