From dbf650b67bb4db1b95807d2aafe2d7cfafd458da Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 20 Oct 2015 13:17:40 -0700 Subject: [PATCH] tcp: fastopen: limit max_qlen Allowing an application to set whatever limit for the list of recently RST fastopen sessions [1] is not wise, as it open ways to deplete kernel memory. Cap the user provided limit by somaxconn sysctl, like listen() backlog. [1] https://tools.ietf.org/html/rfc7413#section-5.1 Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/tcp.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 5dce9705fe84..c906f4534581 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -392,8 +392,9 @@ static inline bool tcp_passive_fastopen(const struct sock *sk) static inline void fastopen_queue_tune(struct sock *sk, int backlog) { struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue; + int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn); - queue->fastopenq.max_qlen = backlog; + queue->fastopenq.max_qlen = min_t(unsigned int, backlog, somaxconn); } static inline void tcp_saved_syn_free(struct tcp_sock *tp) -- 2.20.1