Merge branch 'vsock-some-fixes-due-to-transport-de-assignment'

Stefano Garzarella says:

====================
vsock: some fixes due to transport de-assignment

v1: https://lore.kernel.org/netdev/20250108180617.154053-1-sgarzare@redhat.com/
v2:
- Added patch 3 to cancel the virtio close delayed work when de-assigning
  the transport
- Added patch 4 to clean the socket state after de-assigning the transport
- Added patch 5 as suggested by Michael and Hyunwoo Kim. It's based on
  Hyunwoo Kim and Wongi Lee patch [1] but using WARN_ON and covering more
  functions
- Added R-b/T-b tags

This series includes two patches discussed in the thread started by
Hyunwoo Kim a few weeks ago [1], plus 3 more patches added after some
discussions on v1 (see changelog). All related to the case where a vsock
socket is de-assigned from a transport (e.g., because the connect fails
or is interrupted by a signal) and then assigned to another transport
or to no-one (NULL).

I tested with usual vsock test suite, plus Michal repro [2]. (Note: the repo
works only if a G2H transport is not loaded, e.g. virtio-vsock driver).

The first patch is a fix more appropriate to the problem reported in
that thread, the second patch on the other hand is a related fix but
of a different problem highlighted by Michal Luczaj. It's present only
in vsock_bpf and already handled in af_vsock.c
The third patch is to cancel the virtio close delayed work when de-assigning
the transport, the fourth patch is to clean the socket state after de-assigning
the transport, the last patch adds warnings and prevents null-ptr-deref in
vsock_*[has_data|has_space].

Hyunwoo Kim, Michal, if you can test and report your Tested-by that
would be great!

[1] https://lore.kernel.org/netdev/Z2K%2FI4nlHdfMRTZC@v4bel-B760M-AORUS-ELITE-AX/
[2] https://lore.kernel.org/netdev/2b3062e3-bdaa-4c94-a3c0-2930595b9670@rbox.co/
====================

Link: https://patch.msgid.link/20250110083511.30419-1-sgarzare@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/vmw_vsock/af_vsock.c

@@ -491,6 +491,15 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
 		 */
 		vsk->transport->release(vsk);
 		vsock_deassign_transport(vsk);
+
+		/* transport's release() and destruct() can touch some socket
+		 * state, since we are reassigning the socket to a new transport
+		 * during vsock_connect(), let's reset these fields to have a
+		 * clean state.
+		 */
+		sock_reset_flag(sk, SOCK_DONE);
+		sk->sk_state = TCP_CLOSE;
+		vsk->peer_shutdown = 0;
 	}
 
 	/* We increase the module refcnt to prevent the transport unloading
@@ -870,6 +879,9 @@ EXPORT_SYMBOL_GPL(vsock_create_connected);
 
 s64 vsock_stream_has_data(struct vsock_sock *vsk)
 {
+	if (WARN_ON(!vsk->transport))
+		return 0;
+
 	return vsk->transport->stream_has_data(vsk);
 }
 EXPORT_SYMBOL_GPL(vsock_stream_has_data);
@@ -878,6 +890,9 @@ s64 vsock_connectible_has_data(struct vsock_sock *vsk)
 {
 	struct sock *sk = sk_vsock(vsk);
 
+	if (WARN_ON(!vsk->transport))
+		return 0;
+
 	if (sk->sk_type == SOCK_SEQPACKET)
 		return vsk->transport->seqpacket_has_data(vsk);
 	else
@@ -887,6 +902,9 @@ EXPORT_SYMBOL_GPL(vsock_connectible_has_data);
 
 s64 vsock_stream_has_space(struct vsock_sock *vsk)
 {
+	if (WARN_ON(!vsk->transport))
+		return 0;
+
 	return vsk->transport->stream_has_space(vsk);
 }
 EXPORT_SYMBOL_GPL(vsock_stream_has_space);

net/vmw_vsock/virtio_transport_common.c

@@ -26,6 +26,9 @@
 /* Threshold for detecting small packets to copy */
 #define GOOD_COPY_LEN  128
 
+static void virtio_transport_cancel_close_work(struct vsock_sock *vsk,
+					       bool cancel_timeout);
+
 static const struct virtio_transport *
 virtio_transport_get_ops(struct vsock_sock *vsk)
 {
@@ -1109,6 +1112,8 @@ void virtio_transport_destruct(struct vsock_sock *vsk)
 {
 	struct virtio_vsock_sock *vvs = vsk->trans;
 
+	virtio_transport_cancel_close_work(vsk, true);
+
 	kfree(vvs);
 	vsk->trans = NULL;
 }
@@ -1204,17 +1209,11 @@ static void virtio_transport_wait_close(struct sock *sk, long timeout)
 	}
 }
 
-static void virtio_transport_do_close(struct vsock_sock *vsk,
-				      bool cancel_timeout)
+static void virtio_transport_cancel_close_work(struct vsock_sock *vsk,
+					       bool cancel_timeout)
 {
 	struct sock *sk = sk_vsock(vsk);
 
-	sock_set_flag(sk, SOCK_DONE);
-	vsk->peer_shutdown = SHUTDOWN_MASK;
-	if (vsock_stream_has_data(vsk) <= 0)
-		sk->sk_state = TCP_CLOSING;
-	sk->sk_state_change(sk);
-
 	if (vsk->close_work_scheduled &&
 	    (!cancel_timeout || cancel_delayed_work(&vsk->close_work))) {
 		vsk->close_work_scheduled = false;
@@ -1226,6 +1225,20 @@ static void virtio_transport_do_close(struct vsock_sock *vsk,
 	}
 }
 
+static void virtio_transport_do_close(struct vsock_sock *vsk,
+				      bool cancel_timeout)
+{
+	struct sock *sk = sk_vsock(vsk);
+
+	sock_set_flag(sk, SOCK_DONE);
+	vsk->peer_shutdown = SHUTDOWN_MASK;
+	if (vsock_stream_has_data(vsk) <= 0)
+		sk->sk_state = TCP_CLOSING;
+	sk->sk_state_change(sk);
+
+	virtio_transport_cancel_close_work(vsk, cancel_timeout);
+}
+
 static void virtio_transport_close_timeout(struct work_struct *work)
 {
 	struct vsock_sock *vsk =
@@ -1628,8 +1641,11 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
 
 	lock_sock(sk);
 
-	/* Check if sk has been closed before lock_sock */
-	if (sock_flag(sk, SOCK_DONE)) {
+	/* Check if sk has been closed or assigned to another transport before
+	 * lock_sock (note: listener sockets are not assigned to any transport)
+	 */
+	if (sock_flag(sk, SOCK_DONE) ||
+	    (sk->sk_state != TCP_LISTEN && vsk->transport != &t->transport)) {
 		(void)virtio_transport_reset_no_sock(t, skb);
 		release_sock(sk);
 		sock_put(sk);

net/vmw_vsock/vsock_bpf.c

@@ -77,13 +77,21 @@ static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
 			     size_t len, int flags, int *addr_len)
 {
 	struct sk_psock *psock;
+	struct vsock_sock *vsk;
 	int copied;
 
 	psock = sk_psock_get(sk);
 	if (unlikely(!psock))
 		return __vsock_recvmsg(sk, msg, len, flags);
 
 	lock_sock(sk);
+	vsk = vsock_sk(sk);
+
+	if (!vsk->transport) {
+		copied = -ENODEV;
+		goto out;
+	}
+
 	if (vsock_has_data(sk, psock) && sk_psock_queue_empty(psock)) {
 		release_sock(sk);
 		sk_psock_put(sk, psock);
@@ -108,6 +116,7 @@ static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
 		copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
 	}
 
+out:
 	release_sock(sk);
 	sk_psock_put(sk, psock);