From: Eric Dumazet <eric.duma...@gmail.com>
Date: Tue, 08 Aug 2017 01:41:58 -0700
> From: Eric Dumazet <eduma...@google.com>
>
> 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 <dvyu...@google.com>
> Signed-off-by: Eric Dumazet <eduma...@google.com>
Applied and queued up for -stable.
