virtio/vsock: Improve MSG_ZEROCOPY error handling

Add a missing kfree_skb() to prevent memory leaks.

Fixes: 581512a ("vsock/virtio: MSG_ZEROCOPY flag support")
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Acked-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: mmhal

net/vmw_vsock/virtio_transport_common.c

@@ -400,6 +400,7 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
 			if (virtio_transport_init_zcopy_skb(vsk, skb,
 							    info->msg,
 							    can_zcopy)) {
+				kfree_skb(skb);
 				ret = -ENOMEM;
 				break;
 			}