Re: [PATCH] vsock/virtio: fix kernel panic from virtio_transport_reset_no_sock

On Wed, Mar 06, 2019 at 11:10:41AM +0200, Adalbert Lazăr wrote:

On Wed, 6 Mar 2019 08:41:04 +0000, Stefan Hajnoczi [off-list ref] wrote:

quoted

On Tue, Mar 05, 2019 at 08:01:45PM +0200, Adalbert Lazăr wrote:
The pkt argument is the received packet that we must reply to.
The reply packet is allocated just before line 680 and must be free
explicitly for return -ENOTCONN.

You can avoid the leak and make the code easier to read like this:

  struct virtio_vsock_pkt *reply;

  ...

     ------ avoid reusing 'pkt'
    v
  reply = virtio_transport_alloc_pkt(&info, 0, ...);
  if (!reply)
      return -ENOMEM;

  t = virtio_transport_get_ops();
  if (!t) {
      virtio_transport_free_pkt(reply); <-- prevent memory leak
      return -ENOTCONN;
  }
  return t->send_pkt(reply);

What do you think about Stefano's suggestion, to move the check above
the line were the reply is allocated?

That's fine too.

However a follow up patch to eliminate the confusing way that 'pkt' is
reused is still warranted.  If you are busy I'd be happy to send that
cleanup.

Stefan