From 66d3eadbef831bae87040c388d41c9883c87c3e4 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Tue, 5 Jan 2016 12:06:22 +0100 Subject: [PATCH] batman-adv: Drop immediate batadv_neigh_node free function Orabug: 23330572 [ Upstream commit 2baa753c276f27f8e844637561ad597867aa6fb6 ] It is not allowed to free the memory of an object which is part of a list which is protected by rcu-read-side-critical sections without making sure that no other context is accessing the object anymore. This usually happens by removing the references to this object and then waiting until the rcu grace period is over and no one (allowedly) accesses it anymore. But the _now functions ignore this completely. They free the object directly even when a different context still tries to access it. This has to be avoided and thus these functions must be removed and all functions have to use batadv_neigh_node_free_ref. Fixes: 89652331c00f ("batman-adv: split tq information in neigh_node struct") Signed-off-by: Sven Eckelmann Signed-off-by: Marek Lindner Signed-off-by: Antonio Quartulli Signed-off-by: Greg Kroah-Hartman (cherry picked from commit 620493a90c78ce1bd150d48ca6f624ad964e0c8d) Signed-off-by: Dan Duval --- net/batman-adv/originator.c | 33 ++++++++++----------------------- 1 file changed, 10 insertions(+), 23 deletions(-) diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c index 8327f468972a2..c816c668a9465 100644 --- a/net/batman-adv/originator.c +++ b/net/batman-adv/originator.c @@ -209,21 +209,9 @@ static void batadv_neigh_node_free_rcu(struct rcu_head *rcu) kfree(neigh_node); } -/** - * batadv_neigh_node_free_ref_now - decrement the neighbors refcounter - * and possibly free it (without rcu callback) - * @neigh_node: neigh neighbor to free - */ -static void -batadv_neigh_node_free_ref_now(struct batadv_neigh_node *neigh_node) -{ - if (atomic_dec_and_test(&neigh_node->refcount)) - batadv_neigh_node_free_rcu(&neigh_node->rcu); -} - /** * batadv_neigh_node_free_ref - decrement the neighbors refcounter - * and possibly free it + * and possibly release it * @neigh_node: neigh neighbor to free */ void batadv_neigh_node_free_ref(struct batadv_neigh_node *neigh_node) @@ -495,24 +483,23 @@ batadv_neigh_node_get(const struct batadv_orig_node *orig_node, } /** - * batadv_orig_ifinfo_free_rcu - free the orig_ifinfo object - * @rcu: rcu pointer of the orig_ifinfo object + * batadv_orig_ifinfo_release - release orig_ifinfo from lists and queue for + * free after rcu grace period + * @orig_ifinfo: the orig_ifinfo object to release */ -static void batadv_orig_ifinfo_free_rcu(struct rcu_head *rcu) +static void batadv_orig_ifinfo_release(struct batadv_orig_ifinfo *orig_ifinfo) { - struct batadv_orig_ifinfo *orig_ifinfo; struct batadv_neigh_node *router; - orig_ifinfo = container_of(rcu, struct batadv_orig_ifinfo, rcu); - if (orig_ifinfo->if_outgoing != BATADV_IF_DEFAULT) - batadv_hardif_free_ref_now(orig_ifinfo->if_outgoing); + batadv_hardif_free_ref(orig_ifinfo->if_outgoing); /* this is the last reference to this object */ router = rcu_dereference_protected(orig_ifinfo->router, true); if (router) - batadv_neigh_node_free_ref_now(router); - kfree(orig_ifinfo); + batadv_neigh_node_free_ref(router); + + kfree_rcu(orig_ifinfo, rcu); } /** @@ -523,7 +510,7 @@ static void batadv_orig_ifinfo_free_rcu(struct rcu_head *rcu) void batadv_orig_ifinfo_free_ref(struct batadv_orig_ifinfo *orig_ifinfo) { if (atomic_dec_and_test(&orig_ifinfo->refcount)) - call_rcu(&orig_ifinfo->rcu, batadv_orig_ifinfo_free_rcu); + batadv_orig_ifinfo_release(orig_ifinfo); } /** -- 2.50.1