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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>
This commit is contained in:
Stefano Garzarella 2019-06-28 14:36:59 +02:00 committed by David S. Miller
parent 17dd136738
commit 0d20e56ecc
1 changed files with 9 additions and 6 deletions
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15
net/vmw_vsock/virtio_transport.c
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@ -680,12 +680,6 @@ 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);
@ -740,6 +734,15 @@ 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);