diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 2f871424925e..bf8df824bae3 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -296,7 +296,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 	__u32 cookie = ntohl(th->ack_seq) - 1;
 	struct sock *ret = sk;
 	struct request_sock *req;
-	int mss;
+	int full_space, mss;
 	struct rtable *rt;
 	__u8 rcv_wscale;
 	struct flowi4 fl4;
@@ -389,8 +389,13 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 
 	/* Try to redo what tcp_v4_send_synack did. */
 	req->rsk_window_clamp = tp->window_clamp ? :dst_metric(&rt->dst, RTAX_WINDOW);
+	/* limit the window selection if the user enforce a smaller rx buffer */
+	full_space = tcp_full_space(sk);
+	if (sk->sk_userlocks & SOCK_RCVBUF_LOCK &&
+	    (req->rsk_window_clamp > full_space || req->rsk_window_clamp == 0))
+		req->rsk_window_clamp = full_space;
 
-	tcp_select_initial_window(tcp_full_space(sk), req->mss,
+	tcp_select_initial_window(full_space, req->mss,
 				  &req->rsk_rcv_wnd, &req->rsk_window_clamp,
 				  ireq->wscale_ok, &rcv_wscale,
 				  dst_metric(&rt->dst, RTAX_INITRWND));
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index 0fe8ffcda1d7..d1bfdb9c2f2d 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -141,7 +141,7 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
 	__u32 cookie = ntohl(th->ack_seq) - 1;
 	struct sock *ret = sk;
 	struct request_sock *req;
-	int mss;
+	int full_space, mss;
 	struct dst_entry *dst;
 	__u8 rcv_wscale;
 	u32 tsoff = 0;
@@ -244,7 +244,13 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
 	}
 
 	req->rsk_window_clamp = tp->window_clamp ? :dst_metric(dst, RTAX_WINDOW);
-	tcp_select_initial_window(tcp_full_space(sk), req->mss,
+	/* limit the window selection if the user enforce a smaller rx buffer */
+	full_space = tcp_full_space(sk);
+	if (sk->sk_userlocks & SOCK_RCVBUF_LOCK &&
+	    (req->rsk_window_clamp > full_space || req->rsk_window_clamp == 0))
+		req->rsk_window_clamp = full_space;
+
+	tcp_select_initial_window(full_space, req->mss,
 				  &req->rsk_rcv_wnd, &req->rsk_window_clamp,
 				  ireq->wscale_ok, &rcv_wscale,
 				  dst_metric(dst, RTAX_INITRWND));