batman-adv: Fix reference counting of hardif_neigh_node object for neigh_node
The batadv_neigh_node was specific to a batadv_hardif_neigh_node and held an implicit reference to it. But this reference was never stored in form of a pointer in the batadv_neigh_node itself. Instead batadv_neigh_node_release depends on a consistent state of hard_iface->neigh_list and that batadv_hardif_neigh_get always returns the batadv_hardif_neigh_node object which it has a reference for. But batadv_hardif_neigh_get cannot guarantee that because it is working only with rcu_read_lock on this list. It can therefore happen that a neigh_addr is in this list twice or that batadv_hardif_neigh_get cannot find the batadv_hardif_neigh_node for an neigh_addr due to some other list operations taking place at the same time. Instead add a batadv_hardif_neigh_node pointer directly in batadv_neigh_node which will be used for the reference counter decremented on release of batadv_neigh_node. Fixes: cef63419 ("batman-adv: add list of unique single hop neighbors per hard-interface") Signed-off-by: NSven Eckelmann <sven@narfation.org> Signed-off-by: NMarek Lindner <mareklindner@neomailbox.ch> Signed-off-by: NAntonio Quartulli <a@unstable.cc>
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