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Message-Id: <1444846588-28344-4-git-send-email-edumazet@google.com>
Date: Wed, 14 Oct 2015 11:16:28 -0700
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>,
Eric Dumazet <edumazet@...gle.com>,
Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH v2 net-next 3/3] 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 <edumazet@...gle.com>
---
include/net/inet_connection_sock.h | 9 ++---
include/net/request_sock.h | 19 ----------
net/ipv4/inet_connection_sock.c | 71 ++++++++++++++++++++++++++------------
3 files changed, 51 insertions(+), 48 deletions(-)
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 89ecbc80b2ce..8b0e3d8a4d81 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -268,13 +268,8 @@ struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
struct sock *newsk,
const struct request_sock *req);
-static inline void inet_csk_reqsk_queue_add(struct sock *sk,
- struct request_sock *req,
- struct sock *child)
-{
- reqsk_queue_add(&inet_csk(sk)->icsk_accept_queue, req, sk, child);
-}
-
+void inet_csk_reqsk_queue_add(struct sock *sk, struct request_sock *req,
+ struct sock *child);
void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
unsigned long timeout);
diff --git a/include/net/request_sock.h b/include/net/request_sock.h
index 2e73748956d5..a0dde04eb178 100644
--- a/include/net/request_sock.h
+++ b/include/net/request_sock.h
@@ -186,25 +186,6 @@ static inline bool reqsk_queue_empty(const struct request_sock_queue *queue)
return queue->rskq_accept_head == NULL;
}
-static inline void reqsk_queue_add(struct request_sock_queue *queue,
- struct request_sock *req,
- struct sock *parent,
- struct sock *child)
-{
- spin_lock(&queue->rskq_lock);
- req->sk = child;
- sk_acceptq_added(parent);
-
- if (queue->rskq_accept_head == NULL)
- queue->rskq_accept_head = req;
- else
- queue->rskq_accept_tail->dl_next = req;
-
- queue->rskq_accept_tail = req;
- req->dl_next = NULL;
- spin_unlock(&queue->rskq_lock);
-}
-
static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue,
struct sock *parent)
{
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index a5a1b54915e5..08eaa5e20574 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, const int nr_table_entries)
}
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);
--
2.6.0.rc2.230.g3dd15c0
--
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