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net/mlx5e: Fix nullptr in add_vlan_push_action()

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commit dca59f4a79 upstream.

The result of dev_get_by_index_rcu() is not checked for NULL and then
gets dereferenced immediately.

Also, the RCU lock must be held by the caller of dev_get_by_index_rcu(),
which isn't satisfied by the call stack.

Fix by handling nullptr return value when iflink device is not found.
Add RCU locking around dev_get_by_index_rcu() to avoid possible adverse
effects while iterating over the net_device's hlist.

It is safe not to increment reference count of the net_device pointer in
case of a successful lookup, because it's already handled by VLAN code
during VLAN device registration (see register_vlan_dev and
netdev_upper_dev_link).

Fixes: 278748a95a ("net/mlx5e: Offload TC e-switch rules with egress VLAN device")
Addresses-Coverity: ("Dereference null return value")
Signed-off-by: Dima Chumak <dchumak@nvidia.com>
Reviewed-by: Vlad Buslov <vladbu@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dima Chumak 2021-04-26 15:16:26 +03:00 • committed by Greg Kroah-Hartman
commit 2dde54e76b
1 changed files with 6 additions and 2 deletions
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8
drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
View file

@ -4025,8 +4025,12 @@ static int add_vlan_push_action(struct mlx5e_priv *priv,
if (err)
return err;
*out_dev = dev_get_by_index_rcu(dev_net(vlan_dev),
dev_get_iflink(vlan_dev));
rcu_read_lock();
*out_dev = dev_get_by_index_rcu(dev_net(vlan_dev), dev_get_iflink(vlan_dev));
rcu_read_unlock();
if (!*out_dev)
return -ENODEV;
if (is_vlan_dev(*out_dev))
err = add_vlan_push_action(priv, attr, out_dev, action);