From 8ba60924710cde564a3905588b6219741d6356d0 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 8 Aug 2017 01:41:58 -0700 Subject: [PATCH] tcp: fastopen: tcp_connect() must refresh the route With new TCP_FASTOPEN_CONNECT socket option, there is a possibility to call tcp_connect() while socket sk_dst_cache is either NULL or invalid. +0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4 +0 fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK) = 0 +0 setsockopt(4, SOL_TCP, TCP_FASTOPEN_CONNECT, [1], 4) = 0 +0 connect(4, ..., ...) = 0 << sk->sk_dst_cache becomes obsolete, or even set to NULL >> +1 sendto(4, ..., 1000, MSG_FASTOPEN, ..., ...) = 1000 We need to refresh the route otherwise bad things can happen, especially when syzkaller is running on the host :/ Fixes: 19f6d3f3c8422 ("net/tcp-fastopen: Add new API support") Reported-by: Dmitry Vyukov Signed-off-by: Eric Dumazet Cc: Wei Wang Cc: Yuchung Cheng Acked-by: Wei Wang Acked-by: Yuchung Cheng Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 276406a83a37..b7661a68d498 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -3436,6 +3436,10 @@ int tcp_connect(struct sock *sk) int err; tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_CONNECT_CB); + + if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) + return -EHOSTUNREACH; /* Routing failure or similar. */ + tcp_connect_init(sk); if (unlikely(tp->repair)) { -- 2.20.1