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tcp: handle inet_csk_reqsk_queue_add() failures 

Commit 7716682cc5 ("tcp/dccp: fix another race at listener
dismantle") let inet_csk_reqsk_queue_add() fail, and adjusted
{tcp,dccp}_check_req() accordingly. However, TFO and syncookies
weren't modified, thus leaking allocated resources on error.

Contrary to tcp_check_req(), in both syncookies and TFO cases,
we need to drop the request socket. Also, since the child socket is
created with inet_csk_clone_lock(), we have to unlock it and drop an
extra reference (->sk_refcount is initially set to 2 and
inet_csk_reqsk_queue_add() drops only one ref).

For TFO, we also need to revert the work done by tcp_try_fastopen()
(with reqsk_fastopen_remove()).

Fixes: 7716682cc5 ("tcp/dccp: fix another race at listener dismantle")
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Guillaume Nault 2019-03-08 22:09:47 +01:00 committed by David S. Miller
parent 09073525f8
commit 9d3e1368bb
2 changed files with 13 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
net/ipv4/syncookies.c
View File

@ -216,7 +216,12 @@ struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
refcount_set(&req->rsk_refcnt, 1);
tcp_sk(child)->tsoffset = tsoff;
sock_rps_save_rxhash(child, skb);
inet_csk_reqsk_queue_add(sk, req, child);
if (!inet_csk_reqsk_queue_add(sk, req, child)) {
bh_unlock_sock(child);
sock_put(child);
child = NULL;
reqsk_put(req);
}
} else {
reqsk_free(req);
}

8
net/ipv4/tcp_input.c
View File

@ -6498,7 +6498,13 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
af_ops->send_synack(fastopen_sk, dst, &fl, req,
&foc, TCP_SYNACK_FASTOPEN);
/* Add the child socket directly into the accept queue */
inet_csk_reqsk_queue_add(sk, req, fastopen_sk);
if (!inet_csk_reqsk_queue_add(sk, req, fastopen_sk)) {
reqsk_fastopen_remove(fastopen_sk, req, false);
bh_unlock_sock(fastopen_sk);
sock_put(fastopen_sk);
reqsk_put(req);
goto drop;
}
sk->sk_data_ready(sk);
bh_unlock_sock(fastopen_sk);
sock_put(fastopen_sk);