On Friday, 18 September 2020 05:03:19 CEST Xiyu Yang wrote: > batadv_neigh_node_create() is used to create a neigh node object, whose > fields will be initialized with the specific object. When a new > reference of the specific object is created during the initialization, > its refcount should be increased. > > However, when "neigh_node" object initializes its orig_node field with > the "orig_node" object, the function forgets to hold the refcount of the > "orig_node", causing a potential refcount leak and use-after-free issue > for the reason that the object can be freed in other places. > > Fix this issue by increasing the refcount of orig_node object during the > initialization and adding corresponding batadv_orig_node_put() in > batadv_neigh_node_release().
I will most likely not add this patch because I have concerns that this would
need an active garbage collector to fix the reference counter loop.
Please check batadv_neigh_node::orig_node (whose reference counter you've just
incremented) and batadv_orig_node::neigh_list (with batadv_neigh_node). And at
the same time the batadv_neigh_node_release and batadv_orig_node_release. So
the originator will only free the reference (and thus potentially call
batadv_neigh_node_release) when its own reference counter is zero. But it
cannot become zero because the neigh_node is holding a reference to this
originator.
Kind regards,
Sven
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