[PATCH v2] vsock: notify server to shutdown when client has pending signal

The client's sk_state will be set to TCP_ESTABLISHED if the server
replay the client's connect request.

However, if the client has pending signal, its sk_state will be set
to TCP_CLOSE without notify the server, so the server will hold the
corrupt connection.

            client                        server

1. sk_state=TCP_SYN_SENT         |
2. call ->connect()              |
3. wait reply                    |
                                 | 4. sk_state=TCP_ESTABLISHED
                                 | 5. insert to connected list
                                 | 6. reply to the client
7. sk_state=TCP_ESTABLISHED      |
8. insert to connected list      |
9. *signal pending* <--------------------- the user kill client
10. sk_state=TCP_CLOSE           |
client is exiting...             |
11. call ->release()             |
     virtio_transport_close
      if (!(sk->sk_state == TCP_ESTABLISHED ||
	      sk->sk_state == TCP_CLOSING))
		return true; *return at here, the server cannot notice the connection is corrupt*

So the client should notify the peer in this case.

Cc: David S. Miller <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Jorgen Hansen <redacted>
Cc: Norbert Slusarek <redacted>
Cc: Andra Paraschiv <redacted>
Cc: Colin Ian King <redacted>
Cc: David Brazdil <redacted>
Cc: Alexander Popov <redacted>
Suggested-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lkml.org/lkml/2021/5/17/418
Signed-off-by: lixianming <redacted>
Signed-off-by: Longpeng(Mike) <redacted>
---
 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 92a72f0..ae11311 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c

@@ -1369,7 +1369,7 @@ static int vsock_stream_connect(struct socket *sock, struct sockaddr *addr,
 
 		if (signal_pending(current)) {
 			err = sock_intr_errno(timeout);
-			sk->sk_state = TCP_CLOSE;
+			sk->sk_state = sk->sk_state == TCP_ESTABLISHED ? TCP_CLOSING : TCP_CLOSE;
 			sock->state = SS_UNCONNECTED;
 			vsock_transport_cancel_pkt(vsk);
 			goto out_wait;

-- 
1.8.3.1

On Mon, Jun 21, 2021 at 02:26:01PM +0800, Longpeng(Mike) wrote:

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Mon, 21 Jun 2021 14:26:01 +0800 you wrote:

The client's sk_state will be set to TCP_ESTABLISHED if the server
replay the client's connect request.

However, if the client has pending signal, its sk_state will be set
to TCP_CLOSE without notify the server, so the server will hold the
corrupt connection.

[...]

Here is the summary with links:
  - [v2] vsock: notify server to shutdown when client has pending signal
    https://git.kernel.org/netdev/net/c/c7ff9cff7060

You are awesome, thank you!
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