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devlink: disallow reload operation during device cleanup

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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: 2d8dc5bbf4 ("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>
This commit is contained in:
Jiri Pirko
2019-11-08 21:42:43 +01:00
committed by David S. Miller
parent f95e6c9c46
commit a0c76345e3
5 changed files with 57 additions and 4 deletions
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42
net/core/devlink.c
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@@ -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;
@@ -6308,12 +6311,49 @@ 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);
}
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
*
@@ -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");
}
}