From: Dima Chumak dchumak@nvidia.com
commit dca59f4a791960ec73fa15803faa0abe0f92ece2 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: 278748a95aa3 ("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 --- drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c @@ -3430,8 +3430,12 @@ static int add_vlan_push_action(struct m 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);