Re: [PATCH net] virtio/vsock: fix leak due to missing skb owner

[Stefano Garzarella]

On Mon, Mar 27, 2023 at 10:01:05PM +0000, Bobby Eshleman wrote:
> This patch sets the owner for the skb when being sent from a socket and
> so 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.
>
> Fixes: 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff")
> Signed-off-by: Bobby Eshleman <bobby.eshleman@xxxxxxxxxxxxx>
> Reported-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
> Link: https://lore.kernel.org/all/ZCCbATwov4U+GBUv@pop-os.localdomain/
> ---
> net/vmw_vsock/virtio_transport_common.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> index 957cdc01c8e8..2a2f0c1a9fbd 100644
> --- a/net/vmw_vsock/virtio_transport_common.c
> +++ b/net/vmw_vsock/virtio_transport_common.c
> @@ -94,6 +94,9 @@ virtio_transport_alloc_skb(struct virtio_vsock_pkt_info *info,
> 					 info->op,
> 					 info->flags);
>
> +	if (info->vsk)
> +		skb_set_owner_w(skb, sk_vsock(info->vsk));
> +

Should we do the same also in virtio_transport_recv_pkt()?

The skb in that cases is allocated in drivers/vhost/vsock.c and
net/vmw_vsock/virtio_transport.c using directly
virtio_vsock_alloc_skb(), because we don't know in advance which socket
it belongs to.

Then in virtio_transport_recv_pkt() we look for the socket and queue it
up. This should also solve the problem in vsock_loopback.c where we move
skb from one socket to another.

Thanks,
Stefano