4.9-stable review patch. If anyone has any objections, please let me know.
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From: Guillaume Nault gnault@redhat.com
[ Upstream commit 9d3e1368bb45893a75a5dfb7cd21fdebfa6b47af ]
Commit 7716682cc58e ("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: 7716682cc58e ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/syncookies.c | 7 ++++++- net/ipv4/tcp_input.c | 8 +++++++- 2 files changed, 13 insertions(+), 2 deletions(-)
--- a/net/ipv4/syncookies.c +++ b/net/ipv4/syncookies.c @@ -225,7 +225,12 @@ struct sock *tcp_get_cookie_sock(struct if (child) { atomic_set(&req->rsk_refcnt, 1); 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); } --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -6479,7 +6479,13 @@ int tcp_conn_request(struct request_sock 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);