[PATCH 5.18 048/102] caif_virtio: fix race between virtio_device_ready() and ndo_open()

Greg Kroah-Hartman
2022-07-05T12:32:27Z

From: Jason Wang <jasowang@redhat.com>

commit 11a37eb66812ce6a06b79223ad530eb0e1d7294d upstream.

We currently depend on probe() calling virtio_device_ready() -
which happens after netdev
registration. Since ndo_open() can be called immediately
after register_netdev, this means there exists a race between
ndo_open() and virtio_device_ready(): the driver may start to use the
device (e.g. TX) before DRIVER_OK which violates the spec.

Fix this by switching to use register_netdevice() and protect the
virtio_device_ready() with rtnl_lock() to make sure ndo_open() can
only be called after virtio_device_ready().

Fixes: 0d2e1a2926b18 ("caif_virtio: Introduce caif over virtio")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220620051115.3142-3-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/caif/caif_virtio.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/net/caif/caif_virtio.c
+++ b/drivers/net/caif/caif_virtio.c
@@ -721,13 +721,21 @@ static int cfv_probe(struct virtio_devic
/* Carrier is off until netdevice is opened */
netif_carrier_off(netdev);

+ /* serialize netdev register + virtio_device_ready() with ndo_open() */
+ rtnl_lock();
+
/* register Netdev */
- err = register_netdev(netdev);
+ err = register_netdevice(netdev);
if (err) {
+ rtnl_unlock();
dev_err(&vdev->dev, "Unable to register netdev (%d)\n", err);
goto err;
}

+ virtio_device_ready(vdev);
+
+ rtnl_unlock();
+
debugfs_init(cfv);

return 0;