[PATCH net] mlxsw: core: Unpublish devlink parameters during reload

[PATCH net] mlxsw: core: Unpublish devlink parameters during reload

[Ido Schimmel]

From: Jiri Pirko <jiri@mellanox.com>

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 070c63f20f6c ("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: 98bbf70c1c41 ("mlxsw: spectrum: add "acl_region_rehash_interval" devlink param")
Fixes: 7c62cfb8c574 ("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>
---
 drivers/net/ethernet/mellanox/mlxsw/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/core.c b/drivers/net/ethernet/mellanox/mlxsw/core.c
index 14dcc786926d..4421ab22182f 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/core.c
+++ b/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);
-- 
2.21.0

Re: [PATCH net] mlxsw: core: Unpublish devlink parameters during reload

[David Miller]

From: Ido Schimmel <idosch@idosch.org>
Date: Wed, 30 Oct 2019 11:04:22 +0200

> From: Jiri Pirko <jiri@mellanox.com>
> 
> 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 070c63f20f6c ("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: 98bbf70c1c41 ("mlxsw: spectrum: add "acl_region_rehash_interval" devlink param")
> Fixes: 7c62cfb8c574 ("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>

Applied and queued up for -stable.