vsock: fix locking in vsock_shutdown()

commit 1c5fae9c9a092574398a17facc31c533791ef232 upstream.

In vsock_shutdown() we touched some socket fields without holding the
socket lock, such as 'state' and 'sk_flags'.

Also, after the introduction of multi-transport, we are accessing
'vsk->transport' in vsock_send_shutdown() without holding the lock
and this call can be made while the connection is in progress, so
the transport can change in the meantime.

To avoid issues, we hold the socket lock when we enter in
vsock_shutdown() and release it when we leave.

Among the transports that implement the 'shutdown' callback, only
hyperv_transport acquired the lock. Since the caller now holds it,
we no longer take it.

Fixes: d021c344051a ("VSOCK: Introduce VM Sockets")
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 70e2c4def7a65bc73f1289ebad3883c624431289..bd3a5ef8e59b9d9b5077943d1508bfe9afd4d2ba 100644 (file)
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -830,10 +830,12 @@ static int vsock_shutdown(struct socket *sock, int mode)
         */
 
        sk = sock->sk;
+
+       lock_sock(sk);
        if (sock->state == SS_UNCONNECTED) {
                err = -ENOTCONN;
                if (sk->sk_type == SOCK_STREAM)
-                       return err;
+                       goto out;
        } else {
                sock->state = SS_DISCONNECTING;
                err = 0;
@@ -842,10 +844,8 @@ static int vsock_shutdown(struct socket *sock, int mode)
        /* Receive and send shutdowns are treated alike. */
        mode = mode & (RCV_SHUTDOWN | SEND_SHUTDOWN);
        if (mode) {
-               lock_sock(sk);
                sk->sk_shutdown |= mode;
                sk->sk_state_change(sk);
-               release_sock(sk);
 
                if (sk->sk_type == SOCK_STREAM) {
                        sock_reset_flag(sk, SOCK_DONE);
@@ -853,6 +853,8 @@ static int vsock_shutdown(struct socket *sock, int mode)
                }
        }
 
+out:
+       release_sock(sk);
        return err;
 }