hv_sock: add locking in the open/close/release code paths

Without the patch, when hvs_open_connection() hasn't completely established
a connection (e.g. it has changed sk->sk_state to SS_CONNECTED, but hasn't
inserted the sock into the connected queue), vsock_stream_connect() may see
the sk_state change and return the connection to the userspace, and next
when the userspace closes the connection quickly, hvs_release() may not see
the connection in the connected queue; finally hvs_open_connection()
inserts the connection into the queue, but we won't be able to purge the
connection for ever.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Cathy Avery <cavery@redhat.com>
Cc: Rolf Neugebauer <rolf.neugebauer@docker.com>
Cc: Marcelo Cerri <marcelo.cerri@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
index 14ed5a344cdf302ba3f2d8e9dec4fb7c66fdd239..e21991fe883a7c5f03a3d6eefb52518ef9a67d6c 100644 (file)
--- a/net/vmw_vsock/hyperv_transport.c
+++ b/net/vmw_vsock/hyperv_transport.c
@@ -310,11 +310,15 @@ static void hvs_close_connection(struct vmbus_channel *chan)
        struct sock *sk = get_per_channel_state(chan);
        struct vsock_sock *vsk = vsock_sk(sk);
 
+       lock_sock(sk);
+
        sk->sk_state = SS_UNCONNECTED;
        sock_set_flag(sk, SOCK_DONE);
        vsk->peer_shutdown |= SEND_SHUTDOWN | RCV_SHUTDOWN;
 
        sk->sk_state_change(sk);
+
+       release_sock(sk);
 }
 
 static void hvs_open_connection(struct vmbus_channel *chan)
@@ -344,6 +348,8 @@ static void hvs_open_connection(struct vmbus_channel *chan)
        if (!sk)
                return;
 
+       lock_sock(sk);
+
        if ((conn_from_host && sk->sk_state != VSOCK_SS_LISTEN) ||
            (!conn_from_host && sk->sk_state != SS_CONNECTING))
                goto out;
@@ -395,9 +401,7 @@ static void hvs_open_connection(struct vmbus_channel *chan)
 
                vsock_insert_connected(vnew);
 
-               lock_sock(sk);
                vsock_enqueue_accept(sk, new);
-               release_sock(sk);
        } else {
                sk->sk_state = SS_CONNECTED;
                sk->sk_socket->state = SS_CONNECTED;
@@ -410,6 +414,8 @@ static void hvs_open_connection(struct vmbus_channel *chan)
 out:
        /* Release refcnt obtained when we called vsock_find_bound_socket() */
        sock_put(sk);
+
+       release_sock(sk);
 }
 
 static u32 hvs_get_local_cid(void)
@@ -476,13 +482,21 @@ out:
 
 static void hvs_release(struct vsock_sock *vsk)
 {
+       struct sock *sk = sk_vsock(vsk);
        struct hvsock *hvs = vsk->trans;
-       struct vmbus_channel *chan = hvs->chan;
+       struct vmbus_channel *chan;
 
+       lock_sock(sk);
+
+       sk->sk_state = SS_DISCONNECTING;
+       vsock_remove_sock(vsk);
+
+       release_sock(sk);
+
+       chan = hvs->chan;
        if (chan)
                hvs_shutdown(vsk, RCV_SHUTDOWN | SEND_SHUTDOWN);
 
-       vsock_remove_sock(vsk);
 }
 
 static void hvs_destruct(struct vsock_sock *vsk)