mlxsw: core: Unpublish devlink parameters during reload

The devlink parameter "acl_region_rehash_interval" is a runtime
parameter whose value is stored in a dynamically allocated memory. While
reloading the driver, this memory is freed and then allocated again. A
use-after-free might happen if during this time frame someone tries to
retrieve its value.

Since commit 070c63f2 ("net: devlink: allow to change namespaces
during reload") the use-after-free can be reliably triggered when
reloading the driver into a namespace, as after freeing the memory (via
reload_down() callback) all the parameters are notified.

Fix this by unpublishing and then re-publishing the parameters during
reload.

Fixes: 98bbf70c ("mlxsw: spectrum: add "acl_region_rehash_interval" devlink param")
Fixes: 7c62cfb8 ("devlink: publish params only after driver init is done")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/core.c

@@ -1186,7 +1186,7 @@ __mlxsw_core_bus_device_register(const struct mlxsw_bus_info *mlxsw_bus_info,
 	if (err)
 		goto err_thermal_init;
 
-	if (mlxsw_driver->params_register && !reload)
+	if (mlxsw_driver->params_register)
 		devlink_params_publish(devlink);
 
 	return 0;
@@ -1259,7 +1259,7 @@ void mlxsw_core_bus_device_unregister(struct mlxsw_core *mlxsw_core,
 			return;
 	}
 
-	if (mlxsw_core->driver->params_unregister && !reload)
+	if (mlxsw_core->driver->params_unregister)
 		devlink_params_unpublish(devlink);
 	mlxsw_thermal_fini(mlxsw_core->thermal);
 	mlxsw_hwmon_fini(mlxsw_core->hwmon);