From e226121fcc26e69c721a435aa9348a2f452e4d3e Mon Sep 17 00:00:00 2001 From: Stefano Garzarella <sgarzare@redhat.com> Date: Fri, 5 Jul 2019 13:04:54 +0200 Subject: [PATCH] vsock/virtio: fix flush of works during the .remove() This patch moves the flush of works after vdev->config->del_vqs(vdev), because we need to be sure that no workers run before to free the 'vsock' object. Since we stopped the workers using the [tx|rx|event]_run flags, we are sure no one is accessing the device while we are calling vdev->config->reset(vdev), so we can safely move the workers' flush. Before the vdev->config->del_vqs(vdev), workers can be scheduled by VQ callbacks, so we must flush them after del_vqs(), to avoid use-after-free of 'vsock' object. Suggested-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> --- net/vmw_vsock/virtio_transport.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c index 4dbdce7746bd..0815d1357861 100644 --- a/net/vmw_vsock/virtio_transport.c +++ b/net/vmw_vsock/virtio_transport.c @@ -681,12 +681,6 @@ static void virtio_vsock_remove(struct virtio_device *vdev) rcu_assign_pointer(the_virtio_vsock, NULL); synchronize_rcu(); - 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); @@ -741,6 +735,15 @@ 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. + */ + 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); + mutex_unlock(&the_virtio_vsock_mutex); kfree(vsock);