From: Dima Chumak Date: Mon, 26 Apr 2021 12:16:26 +0000 (+0300) Subject: net/mlx5e: Fix nullptr in add_vlan_push_action() X-Git-Tag: v5.4.124~104 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=4fd3213e53547341d23374feba9bb7c3c4c76f9e;p=thirdparty%2Fkernel%2Fstable.git net/mlx5e: Fix nullptr in add_vlan_push_action() 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 Reviewed-by: Vlad Buslov Signed-off-by: Saeed Mahameed Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c index 6495c26d95969..fe7342e8a043b 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c @@ -3170,8 +3170,12 @@ 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);