vsock: fix locking in vsock_shutdown()

stable inclusion
from stable-5.10.17
commit 69e9fd9de17e839920149e0906f4758667d3cee7
bugzilla: 48169

--------------------------------

commit 1c5fae9c 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: d021c344 ("VSOCK: Introduce VM Sockets")
Signed-off-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

net/vmw_vsock/af_vsock.c

@@ -926,10 +926,12 @@ 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;
@@ -938,10 +940,8 @@ 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);
@@ -949,6 +949,8 @@ static int vsock_shutdown(struct socket *sock, int mode)
 		}
 	}
 
+out:
+	release_sock(sk);
 	return err;
 }
 

net/vmw_vsock/hyperv_transport.c

@@ -474,14 +474,10 @@ static void hvs_shutdown_lock_held(struct hvsock *hvs, int mode)
 
 static int hvs_shutdown(struct vsock_sock *vsk, int mode)
 {
-	struct sock *sk = sk_vsock(vsk);
-
 	if (!(mode & SEND_SHUTDOWN))
 		return 0;
 
-	lock_sock(sk);
 	hvs_shutdown_lock_held(vsk->trans, mode);
-	release_sock(sk);
 	return 0;
 }