Messages in this thread | | | Subject | Re: [PATCH 3/4] vsock/virtio: fix flush of works during the .remove() | From | Jason Wang <> | Date | Wed, 29 May 2019 11:22:40 +0800 |
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On 2019/5/28 下午6:56, Stefano Garzarella wrote: > We flush all pending works before to call vdev->config->reset(vdev), > but other works can be queued before the vdev->config->del_vqs(vdev), > so we add another flush after it, to avoid use after free. > > Suggested-by: Michael S. Tsirkin <mst@redhat.com> > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> > --- > net/vmw_vsock/virtio_transport.c | 23 +++++++++++++++++------ > 1 file changed, 17 insertions(+), 6 deletions(-) > > diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c > index e694df10ab61..ad093ce96693 100644 > --- a/net/vmw_vsock/virtio_transport.c > +++ b/net/vmw_vsock/virtio_transport.c > @@ -660,6 +660,15 @@ static int virtio_vsock_probe(struct virtio_device *vdev) > return ret; > } > > +static void virtio_vsock_flush_works(struct virtio_vsock *vsock) > +{ > + flush_work(&vsock->loopback_work); > + flush_work(&vsock->rx_work); > + flush_work(&vsock->tx_work); > + flush_work(&vsock->event_work); > + flush_work(&vsock->send_pkt_work); > +} > + > static void virtio_vsock_remove(struct virtio_device *vdev) > { > struct virtio_vsock *vsock = vdev->priv; > @@ -668,12 +677,6 @@ static void virtio_vsock_remove(struct virtio_device *vdev) > mutex_lock(&the_virtio_vsock_mutex); > the_virtio_vsock = NULL; > > - flush_work(&vsock->loopback_work); > - flush_work(&vsock->rx_work); > - flush_work(&vsock->tx_work); > - flush_work(&vsock->event_work); > - flush_work(&vsock->send_pkt_work); > - > /* Reset all connected sockets when the device disappear */ > vsock_for_each_connected_socket(virtio_vsock_reset_sock); > > @@ -690,6 +693,9 @@ static void virtio_vsock_remove(struct virtio_device *vdev) > vsock->event_run = false; > mutex_unlock(&vsock->event_lock); > > + /* Flush all pending works */ > + virtio_vsock_flush_works(vsock); > + > /* Flush all device writes and interrupts, device will not use any > * more buffers. > */ > @@ -726,6 +732,11 @@ static void virtio_vsock_remove(struct virtio_device *vdev) > /* Delete virtqueues and flush outstanding callbacks if any */ > vdev->config->del_vqs(vdev); > > + /* Other works can be queued before 'config->del_vqs()', so we flush > + * all works before to free the vsock object to avoid use after free. > + */ > + virtio_vsock_flush_works(vsock);
Some questions after a quick glance:
1) It looks to me that the work could be queued from the path of vsock_transport_cancel_pkt() . Is that synchronized here?
2) If we decide to flush after dev_vqs(), is tx_run/rx_run/event_run still needed? It looks to me we've already done except that we need flush rx_work in the end since send_pkt_work can requeue rx_work.
Thanks
> + > kfree(vsock); > mutex_unlock(&the_virtio_vsock_mutex); > }
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