devlink: disallow reload operation during device cleanup

There is a race between driver code that does setup/cleanup of device
and devlink reload operation that in some drivers works with the same
code. Use after free could we easily obtained by running:

while true; do
        echo 10 > /sys/bus/netdevsim/new_device
        devlink dev reload netdevsim/netdevsim10 &
        echo 10 > /sys/bus/netdevsim/del_device
done

Fix this by enabling reload only after setup of device is complete and
disabling it at the beginning of the cleanup process.

Reported-by: Ido Schimmel <[email protected]>
Fixes: 2d8dc5bbf4e7 ("devlink: Add support for reload")
Signed-off-by: Jiri Pirko <[email protected]>
Acked-by: Jakub Kicinski <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c
index 3da96c7e8265..059711edfc61 100644
--- a/drivers/net/netdevsim/dev.c
+++ b/drivers/net/netdevsim/dev.c
@@ -820,6 +820,7 @@ int nsim_dev_probe(struct nsim_bus_dev *nsim_bus_dev)
 		goto err_bpf_dev_exit;
 
 	devlink_params_publish(devlink);
+	devlink_reload_enable(devlink);
 	return 0;
 
 err_bpf_dev_exit:
@@ -865,6 +866,8 @@ void nsim_dev_remove(struct nsim_bus_dev *nsim_bus_dev)
 	struct nsim_dev *nsim_dev = dev_get_drvdata(&nsim_bus_dev->dev);
 	struct devlink *devlink = priv_to_devlink(nsim_dev);
 
+	devlink_reload_disable(devlink);
+
 	nsim_dev_reload_destroy(nsim_dev);
 
 	nsim_bpf_dev_exit(nsim_dev);