Re: [PATCH v2] vsock: remove vsock from connected table when connect is interrupted by a signal

[Stefano Garzarella]

On Thu, Feb 17, 2022 at 08:13:12AM -0600, Seth Forshee wrote:
> vsock_connect() expects that the socket could already be in the
> TCP_ESTABLISHED state when the connecting task wakes up with a signal
> pending. If this happens the socket will be in the connected table, and
> it is not removed when the socket state is reset. In this situation it's
> common for the process to retry connect(), and if the connection is
> successful the socket will be added to the connected table a second
> time, corrupting the list.
>
> Prevent this by calling vsock_remove_connected() if a signal is received
> while waiting for a connection. This is harmless if the socket is not in
> the connected table, and if it is in the table then removing it will
> prevent list corruption from a double add.
>
> Note for backporting: this patch requires d5afa82c977e ("vsock: correct
> removal of socket from the list"), which is in all current stable trees
> except 4.9.y.
>
> Fixes: d021c344051a ("VSOCK: Introduce VM Sockets")
> Signed-off-by: Seth Forshee <sforshee@xxxxxxxxxxxxxxxx>
> ---
> v2: Add Fixes tag and backporting notes.
> ---
> net/vmw_vsock/af_vsock.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> index 3235261f138d..38baeb189d4e 100644
> --- a/net/vmw_vsock/af_vsock.c
> +++ b/net/vmw_vsock/af_vsock.c
> @@ -1401,6 +1401,7 @@ static int vsock_connect(struct socket *sock, struct sockaddr *addr,
> 			sk->sk_state = sk->sk_state == TCP_ESTABLISHED ? TCP_CLOSING : TCP_CLOSE;
> 			sock->state = SS_UNCONNECTED;
> 			vsock_transport_cancel_pkt(vsk);
> +			vsock_remove_connected(vsk);
> 			goto out_wait;
> 		} else if (timeout == 0) {
> 			err = -ETIMEDOUT;
> --
> 2.32.0

Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>