The function batadv_gw_node_add is responsible for adding new gw_node to the gateway_list. It is expecting that the caller already checked that there is not already an entry with the same key or not.

But the lock for the list is only held when the list is really modified. This could lead to duplicated entries because another context could create an entry with the same key between the check and the list manipulation.

The check and the manipulation of the list must therefore be in the same locked code section.

Fixes: bc3538cabac5 ("batman-adv: adding gateway functionality") Signed-off-by: Sven Eckelmann sven@narfation.org Acked-by: Marek Lindner mareklindner@neomailbox.ch --- v2: * added kerneldoc about the locking requirements

net/batman-adv/gateway_client.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c index 8b198ee7..140c61a3 100644 --- a/net/batman-adv/gateway_client.c +++ b/net/batman-adv/gateway_client.c @@ -32,6 +32,7 @@ #include <linux/kernel.h> #include <linux/kref.h> #include <linux/list.h> +#include <linux/lockdep.h> #include <linux/netdevice.h> #include <linux/netlink.h> #include <linux/rculist.h> @@ -348,6 +349,9 @@ void batadv_gw_check_election(struct batadv_priv *bat_priv, * @bat_priv: the bat priv with all the soft interface information * @orig_node: originator announcing gateway capabilities * @gateway: announced bandwidth information + * + * Has to be called with the appropriate locks being acquired + * (gw.list_lock). */ static void batadv_gw_node_add(struct batadv_priv *bat_priv, struct batadv_orig_node *orig_node, @@ -355,6 +359,8 @@ static void batadv_gw_node_add(struct batadv_priv *bat_priv, { struct batadv_gw_node *gw_node;

+ lockdep_assert_held(&bat_priv->gw.list_lock); + if (gateway->bandwidth_down == 0) return;

@@ -369,10 +375,8 @@ static void batadv_gw_node_add(struct batadv_priv *bat_priv, gw_node->bandwidth_down = ntohl(gateway->bandwidth_down); gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);

- spin_lock_bh(&bat_priv->gw.list_lock); kref_get(&gw_node->refcount); hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.gateway_list); - spin_unlock_bh(&bat_priv->gw.list_lock);

batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n", @@ -428,11 +432,14 @@ void batadv_gw_node_update(struct batadv_priv *bat_priv, { struct batadv_gw_node *gw_node, *curr_gw = NULL;

+ spin_lock_bh(&bat_priv->gw.list_lock); gw_node = batadv_gw_node_get(bat_priv, orig_node); if (!gw_node) { batadv_gw_node_add(bat_priv, orig_node, gateway); + spin_unlock_bh(&bat_priv->gw.list_lock); goto out; } + spin_unlock_bh(&bat_priv->gw.list_lock);

if (gw_node->bandwidth_down == ntohl(gateway->bandwidth_down) && gw_node->bandwidth_up == ntohl(gateway->bandwidth_up))

The function batadv_softif_vlan_get is responsible for adding new softif_vlan to the softif_vlan_list. It first checks whether the entry already is in the list or not. If it is, then the creation of a new entry is aborted.

But the lock for the list is only held when the list is really modified. This could lead to duplicated entries because another context could create an entry with the same key between the check and the list manipulation.

The check and the manipulation of the list must therefore be in the same locked code section.

Fixes: 952cebb57518 ("batman-adv: add per VLAN interface attribute framework") Signed-off-by: Sven Eckelmann sven@narfation.org --- v2: * changed batadv_softif_create_vlan to handle problems in batadv_sysfs_add_vlan as fatal error

net/batman-adv/soft-interface.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c index 1485263a..626ddca3 100644 --- a/net/batman-adv/soft-interface.c +++ b/net/batman-adv/soft-interface.c @@ -574,15 +574,20 @@ int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid) struct batadv_softif_vlan *vlan; int err;

+ spin_lock_bh(&bat_priv->softif_vlan_list_lock); + vlan = batadv_softif_vlan_get(bat_priv, vid); if (vlan) { batadv_softif_vlan_put(vlan); + spin_unlock_bh(&bat_priv->softif_vlan_list_lock); return -EEXIST; }

vlan = kzalloc(sizeof(*vlan), GFP_ATOMIC); - if (!vlan) + if (!vlan) { + spin_unlock_bh(&bat_priv->softif_vlan_list_lock); return -ENOMEM; + }

vlan->bat_priv = bat_priv; vlan->vid = vid; @@ -590,17 +595,23 @@ int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid)

atomic_set(&vlan->ap_isolation, 0);

+ kref_get(&vlan->refcount); + hlist_add_head_rcu(&vlan->list, &bat_priv->softif_vlan_list); + spin_unlock_bh(&bat_priv->softif_vlan_list_lock); + + /* batadv_sysfs_add_vlan cannot be in the spinlock section due to the + * sleeping behavior of the sysfs functions and the fs_reclaim lock + */ err = batadv_sysfs_add_vlan(bat_priv->soft_iface, vlan); if (err) { - kfree(vlan); + /* ref for the function */ + batadv_softif_vlan_put(vlan); + + /* ref for the list */ + batadv_softif_vlan_put(vlan); return err; }

- spin_lock_bh(&bat_priv->softif_vlan_list_lock); - kref_get(&vlan->refcount); - hlist_add_head_rcu(&vlan->list, &bat_priv->softif_vlan_list); - spin_unlock_bh(&bat_priv->softif_vlan_list_lock); - /* add a new TT local entry. This one will be marked with the NOPURGE * flag */

The function batadv_tvlv_handler_register is responsible for adding new tvlv_handler to the handler_list. It first checks whether the entry already is in the list or not. If it is, then the creation of a new entry is aborted.

But the lock for the list is only held when the list is really modified. This could lead to duplicated entries because another context could create an entry with the same key between the check and the list manipulation.

The check and the manipulation of the list must therefore be in the same locked code section.

Fixes: 0b6aa0d43767 ("batman-adv: tvlv - basic infrastructure") Signed-off-by: Sven Eckelmann sven@narfation.org Acked-by: Marek Lindner mareklindner@neomailbox.ch --- net/batman-adv/tvlv.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/batman-adv/tvlv.c b/net/batman-adv/tvlv.c index a6374582..40e69c93 100644 --- a/net/batman-adv/tvlv.c +++ b/net/batman-adv/tvlv.c @@ -529,15 +529,20 @@ void batadv_tvlv_handler_register(struct batadv_priv *bat_priv, { struct batadv_tvlv_handler *tvlv_handler;

+ spin_lock_bh(&bat_priv->tvlv.handler_list_lock); + tvlv_handler = batadv_tvlv_handler_get(bat_priv, type, version); if (tvlv_handler) { + spin_unlock_bh(&bat_priv->tvlv.handler_list_lock); batadv_tvlv_handler_put(tvlv_handler); return; }

tvlv_handler = kzalloc(sizeof(*tvlv_handler), GFP_ATOMIC); - if (!tvlv_handler) + if (!tvlv_handler) { + spin_unlock_bh(&bat_priv->tvlv.handler_list_lock); return; + }

tvlv_handler->ogm_handler = optr; tvlv_handler->unicast_handler = uptr; @@ -547,7 +552,6 @@ void batadv_tvlv_handler_register(struct batadv_priv *bat_priv, kref_init(&tvlv_handler->refcount); INIT_HLIST_NODE(&tvlv_handler->list);

- spin_lock_bh(&bat_priv->tvlv.handler_list_lock); kref_get(&tvlv_handler->refcount); hlist_add_head_rcu(&tvlv_handler->list, &bat_priv->tvlv.handler_list); spin_unlock_bh(&bat_priv->tvlv.handler_list_lock);