From: Eric Dumazet <edumazet@google.com>
Date: Tue, 8 Aug 2017 01:41:58 -0700
Subject: [PATCH] tcp: fastopen: tcp_connect() must refresh the route
References: bnc#1060662
Patch-mainline: 4.12.7
Git-commit: 8ba60924710cde564a3905588b6219741d6356d0
[ Upstream commit 8ba60924710cde564a3905588b6219741d6356d0 ]
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 <dvyukov@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Wei Wang <weiwan@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Acked-by: Wei Wang <weiwan@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
net/ipv4/tcp_output.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 4858e190f6ac..8963b8c5fb41 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3361,6 +3361,9 @@ int tcp_connect(struct sock *sk)
struct sk_buff *buff;
int err;
+ if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk))
+ return -EHOSTUNREACH; /* Routing failure or similar. */
+
tcp_connect_init(sk);
if (unlikely(tp->repair)) {
--
2.14.2