From: Eric Dumazet <[email protected]>
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 <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
Cc: Wei Wang <[email protected]>
Cc: Yuchung Cheng <[email protected]>
---
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)) {
