virtio/vsock: check transport before skb allocation

Pointer to transport could be checked before allocation of skbuff, thus
there is no need to free skbuff when this pointer is NULL.
Signed-off-by: NArseniy Krasnov <AVKrasnov@sberdevices.ru>
Reviewed-by: NBobby Eshleman <bobby.eshleman@bytedance.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Reviewed-by: NPavan Chebbi <pavan.chebbi@broadcom.com>
Link: https://lore.kernel.org/r/08d61bef-0c11-c7f9-9266-cb2109070314@sberdevices.ruSigned-off-by: NPaolo Abeni <pabeni@redhat.com>

net/vmw_vsock/virtio_transport_common.c

@@ -850,6 +850,9 @@ static int virtio_transport_reset_no_sock(const struct virtio_transport *t,
 	if (le16_to_cpu(hdr->op) == VIRTIO_VSOCK_OP_RST)
 		return 0;
 
+	if (!t)
+		return -ENOTCONN;
+
 	reply = virtio_transport_alloc_skb(&info, 0,
 					   le64_to_cpu(hdr->dst_cid),
 					   le32_to_cpu(hdr->dst_port),
@@ -858,11 +861,6 @@ static int virtio_transport_reset_no_sock(const struct virtio_transport *t,
 	if (!reply)
 		return -ENOMEM;
 
-	if (!t) {
-		kfree_skb(reply);
-		return -ENOTCONN;
-	}
-
 	return t->send_pkt(reply);
 }