linux-kernel - Re: [PATCH] vsock: bugfix port residue in server

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Message-ID: <ftuh7vhoxdxbymg6u3wlkfhlfoufupeqampqxc2ktqrpxndow3@dkpufdnuwlln>
Date:   Wed, 10 May 2023 17:23:14 +0200
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     Zhuang Shengen <zhuangshengen@...wei.com>
Cc:     virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        arei.gonglei@...wei.com, longpeng2@...wei.com,
        jianjay.zhou@...wei.com
Subject: Re: [PATCH] vsock: bugfix port residue in server

Hi,
thanks for the patch, the change LGTM, but I have the following
suggestions:

Please avoid "bugfix" in the subject, "fix" should be enough:
https://www.kernel.org/doc/html/v4.17/process/submitting-patches.html#describe-your-changes

Anyway, I suggest to change the subject in
"vsock: avoid to close connected socket after the timeout"

On Wed, May 10, 2023 at 10:25:02PM +0800, Zhuang Shengen wrote:
>When client and server establish a connection through vsock,
>the client send a request to the server to initiate the connection,
>then start a timer to wait for the server's response. When the server's
>RESPONSE message arrives, the timer also times out and exits. The
>server's RESPONSE message is processed first, and the connection is
>established. However, the client's timer also times out, the original
>processing logic of the client is to directly set the state of this vsock
>to CLOSE and return ETIMEDOUT, User will release the port. It will not

What to you mean with "User" here?

>notify the server when the port is released, causing the server port remain
>

Can we remove this blank line?

>when client's vsock_connect timeout，it should check sk state is

The remote peer can't trust the other peer, indeed it will receive an
error after sending the first message and it will remove the connection,
right?

>ESTABLISHED or not. if sk state is ESTABLISHED, it means the connection
>is established, the client should not set the sk state to CLOSE
>
>Note: I encountered this issue on kernel-4.18, which can be fixed by
>this patch. Then I checked the latest code in the community
>and found similar issue.
>

In order to backport it to the stable kernels, we should add a Fixes tag:
https://www.kernel.org/doc/html/v4.17/process/submitting-patches.html#describe-your-changes

Thanks,
Stefano

>Signed-off-by: Zhuang Shengen <zhuangshengen@...wei.com>
>---
> net/vmw_vsock/af_vsock.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index 413407bb646c..efb8a0937a13 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -1462,7 +1462,7 @@ static int vsock_connect(struct socket *sock, struct sockaddr *addr,
> 			vsock_transport_cancel_pkt(vsk);
> 			vsock_remove_connected(vsk);
> 			goto out_wait;
>-		} else if (timeout == 0) {
>+		} else if ((sk->sk_state != TCP_ESTABLISHED) && (timeout == 0)) {
> 			err = -ETIMEDOUT;
> 			sk->sk_state = TCP_CLOSE;
> 			sock->state = SS_UNCONNECTED;
>-- 
>2.27.0
>