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 <idosch@mellanox.com>
Fixes: 2d8dc5bbf4e7 ("devlink: Add support for reload")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/devlink.c b/net/core/devlink.c
index ff53f7d..2e027c9 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -2791,6 +2791,9 @@ static int devlink_reload(struct devlink *devlink, struct net *dest_net,
{
int err;
+ if (!devlink->reload_enabled)
+ return -EOPNOTSUPP;
+
err = devlink->ops->reload_down(devlink, !!dest_net, extack);
if (err)
return err;
@@ -6308,6 +6311,8 @@ EXPORT_SYMBOL_GPL(devlink_register);
void devlink_unregister(struct devlink *devlink)
{
mutex_lock(&devlink_mutex);
+ WARN_ON(devlink_reload_supported(devlink) &&
+ devlink->reload_enabled);
devlink_notify(devlink, DEVLINK_CMD_DEL);
list_del(&devlink->list);
mutex_unlock(&devlink_mutex);
@@ -6315,6 +6320,41 @@ void devlink_unregister(struct devlink *devlink)
EXPORT_SYMBOL_GPL(devlink_unregister);
/**
+ * devlink_reload_enable - Enable reload of devlink instance
+ *
+ * @devlink: devlink
+ *
+ * Should be called at end of device initialization
+ * process when reload operation is supported.
+ */
+void devlink_reload_enable(struct devlink *devlink)
+{
+ mutex_lock(&devlink_mutex);
+ devlink->reload_enabled = true;
+ mutex_unlock(&devlink_mutex);
+}
+EXPORT_SYMBOL_GPL(devlink_reload_enable);
+
+/**
+ * devlink_reload_disable - Disable reload of devlink instance
+ *
+ * @devlink: devlink
+ *
+ * Should be called at the beginning of device cleanup
+ * process when reload operation is supported.
+ */
+void devlink_reload_disable(struct devlink *devlink)
+{
+ mutex_lock(&devlink_mutex);
+ /* Mutex is taken which ensures that no reload operation is in
+ * progress while setting up forbidded flag.
+ */
+ devlink->reload_enabled = false;
+ mutex_unlock(&devlink_mutex);
+}
+EXPORT_SYMBOL_GPL(devlink_reload_disable);
+
+/**
* devlink_free - Free devlink instance resources
*
* @devlink: devlink
@@ -8201,7 +8241,7 @@ static void __net_exit devlink_pernet_pre_exit(struct net *net)
if (WARN_ON(!devlink_reload_supported(devlink)))
continue;
err = devlink_reload(devlink, &init_net, NULL);
- if (err)
+ if (err && err != -EOPNOTSUPP)
pr_warn("Failed to reload devlink instance into init_net\n");
}
}