From: Kuniyuki Iwashima <kuniyu@amazon.com>
To: <edumazet@google.com>
Cc: <davem@davemloft.net>, <eric.dumazet@gmail.com>,
<kuba@kernel.org>, <netdev@vger.kernel.org>, <pabeni@redhat.com>,
<kuniyu@amazon.com>
Subject: Re: [PATCH net] net: datagram: fix data-races in datagram_poll()
Date: Tue, 9 May 2023 15:50:31 -0700 [thread overview]
Message-ID: <20230509225031.19553-1-kuniyu@amazon.com> (raw)
In-Reply-To: <20230509173131.3263780-1-edumazet@google.com>
From: Eric Dumazet <edumazet@google.com>
Date: Tue, 9 May 2023 17:31:31 +0000
> datagram_poll() runs locklessly, we should add READ_ONCE()
> annotations while reading sk->sk_err, sk->sk_shutdown and sk->sk_state.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
> ---
> net/core/datagram.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/net/core/datagram.c b/net/core/datagram.c
> index 5662dff3d381a92b271d9cba38a28a6a8478c114..176eb58347461b160890ce2d6b2d3cbc7412e321 100644
> --- a/net/core/datagram.c
> +++ b/net/core/datagram.c
> @@ -807,18 +807,21 @@ __poll_t datagram_poll(struct file *file, struct socket *sock,
> {
> struct sock *sk = sock->sk;
> __poll_t mask;
> + u8 shutdown;
>
> sock_poll_wait(file, sock, wait);
> mask = 0;
>
> /* exceptional events? */
> - if (sk->sk_err || !skb_queue_empty_lockless(&sk->sk_error_queue))
> + if (READ_ONCE(sk->sk_err) ||
> + !skb_queue_empty_lockless(&sk->sk_error_queue))
> mask |= EPOLLERR |
> (sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? EPOLLPRI : 0);
>
> - if (sk->sk_shutdown & RCV_SHUTDOWN)
> + shutdown = READ_ONCE(sk->sk_shutdown);
> + if (shutdown & RCV_SHUTDOWN)
> mask |= EPOLLRDHUP | EPOLLIN | EPOLLRDNORM;
> - if (sk->sk_shutdown == SHUTDOWN_MASK)
> + if (shutdown == SHUTDOWN_MASK)
> mask |= EPOLLHUP;
>
> /* readable? */
> @@ -827,10 +830,12 @@ __poll_t datagram_poll(struct file *file, struct socket *sock,
>
> /* Connection-based need to check for termination and startup */
> if (connection_based(sk)) {
> - if (sk->sk_state == TCP_CLOSE)
> + int state = READ_ONCE(sk->sk_state);
> +
> + if (state == TCP_CLOSE)
> mask |= EPOLLHUP;
> /* connection hasn't started yet? */
> - if (sk->sk_state == TCP_SYN_SENT)
> + if (state == TCP_SYN_SENT)
> return mask;
> }
>
> --
> 2.40.1.521.gf1e218fcd8-goog
next prev parent reply other threads:[~2023-05-09 22:50 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-09 17:31 [PATCH net] net: datagram: fix data-races in datagram_poll() Eric Dumazet
2023-05-09 22:50 ` Kuniyuki Iwashima [this message]
2023-05-11 2:10 ` patchwork-bot+netdevbpf
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