Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 08/16] tcp: fastopen: tcp_connect() must refresh the route | Date | Fri, 11 Aug 2017 15:01:38 -0700 |
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4.9-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet <edumazet@google.com>
[ 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> --- net/ipv4/tcp_output.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -3344,6 +3344,9 @@ 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)) {
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