virtio/vsock: fix leaks due to missing skb owner

commit f9d2b1e upstream.

This patch sets the skb owner in the recv and send path for virtio.

For the send path, this solves the leak caused when
virtio_transport_purge_skbs() finds skb->sk is always NULL and therefore
never matches it with the current socket. Setting the owner upon
allocation fixes this.

For the recv path, this ensures correctness of accounting and also
correct transfer of ownership in vsock_loopback (when skbs are sent from
one socket and received by another).

Fixes: 71dc9ec ("virtio/vsock: replace virtio_vsock_pkt with sk_buff")
Signed-off-by: Bobby Eshleman <[email protected]>
Reported-by: Cong Wang <[email protected]>
Link: https://lore.kernel.org/all/[email protected]/
Reviewed-by: Stefano Garzarella <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

net/vmw_vsock/virtio_transport_common.c

@@ -94,6 +94,11 @@ virtio_transport_alloc_skb(struct virtio_vsock_pkt_info *info,
 					 info->op,
 					 info->flags);
 
+	if (info->vsk && !skb_set_owner_sk_safe(skb, sk_vsock(info->vsk))) {
+		WARN_ONCE(1, "failed to allocate skb on vsock socket with sk_refcnt == 0\n");
+		goto out;
+	}
+
 	return skb;
 
 out:
@@ -1302,6 +1307,11 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
 		goto free_pkt;
 	}
 
+	if (!skb_set_owner_sk_safe(skb, sk)) {
+		WARN_ONCE(1, "receiving vsock socket has sk_refcnt == 0\n");
+		goto free_pkt;
+	}
+
 	vsk = vsock_sk(sk);
 
 	lock_sock(sk);