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Subject[PATCH 4.19 15/24] mlxsw: core: Fix devlink unregister flow
Date
4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Shalom Toledo <shalomt@mellanox.com>

[ Upstream commit a22712a962912faf257e857ab6857f56a93cfb34 ]

After a failed reload, the driver is still registered to devlink, its
devlink instance is still allocated and the 'reload_fail' flag is set.
Then, in the next reload try, the driver's allocated devlink instance will
be freed without unregistering from devlink and its components (e.g,
resources). This scenario can cause a use-after-free if the user tries to
execute command via devlink user-space tool.

Fix by not freeing the devlink instance during reload (failed or not).

Fixes: 24cc68ad6c46 ("mlxsw: core: Add support for reload")
Signed-off-by: Shalom Toledo <shalomt@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/mellanox/mlxsw/core.c | 24 +++++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlxsw/core.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core.c
@@ -943,8 +943,8 @@ static int mlxsw_devlink_core_bus_device
mlxsw_core->bus,
mlxsw_core->bus_priv, true,
devlink);
- if (err)
- mlxsw_core->reload_fail = true;
+ mlxsw_core->reload_fail = !!err;
+
return err;
}

@@ -1083,8 +1083,15 @@ void mlxsw_core_bus_device_unregister(st
{
struct devlink *devlink = priv_to_devlink(mlxsw_core);

- if (mlxsw_core->reload_fail)
- goto reload_fail;
+ if (mlxsw_core->reload_fail) {
+ if (!reload)
+ /* Only the parts that were not de-initialized in the
+ * failed reload attempt need to be de-initialized.
+ */
+ goto reload_fail_deinit;
+ else
+ return;
+ }

if (mlxsw_core->driver->fini)
mlxsw_core->driver->fini(mlxsw_core);
@@ -1098,9 +1105,12 @@ void mlxsw_core_bus_device_unregister(st
if (!reload)
devlink_resources_unregister(devlink, NULL);
mlxsw_core->bus->fini(mlxsw_core->bus_priv);
- if (reload)
- return;
-reload_fail:
+
+ return;
+
+reload_fail_deinit:
+ devlink_unregister(devlink);
+ devlink_resources_unregister(devlink, NULL);
devlink_free(devlink);
}
EXPORT_SYMBOL(mlxsw_core_bus_device_unregister);

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