Commit 7b36e8ee authored by Marek Lindner's avatar Marek Lindner
Browse files

batman-adv: Correct rcu refcounting for orig_node 



It might be possible that 2 threads access the same data in the same
rcu grace period. The first thread calls call_rcu() to decrement the
refcount and free the data while the second thread increases the
refcount to use the data. To avoid this race condition all refcount
operations have to be atomic.

Reported-by: default avatarSven Eckelmann <sven@narfation.org>
Signed-off-by: default avatarMarek Lindner <lindner_marek@yahoo.de>
parent 7aadf889

net/batman-adv/gateway_client.c

+4 −2
Original line number Diff line number Diff line
@@ -53,9 +53,11 @@ void *gw_get_selected(struct bat_priv *bat_priv) 
		goto out;



	orig_node = curr_gateway_tmp->orig_node;

	if (!orig_node)

		goto out;



	if (orig_node)

		kref_get(&orig_node->refcount);

	if (!atomic_inc_not_zero(&orig_node->refcount))

		orig_node = NULL;



out:

	rcu_read_unlock();

net/batman-adv/icmp_socket.c

+1 −1
Original line number Diff line number Diff line
@@ -271,7 +271,7 @@ out: 
	if (neigh_node)

		neigh_node_free_ref(neigh_node);

	if (orig_node)

		kref_put(&orig_node->refcount, orig_node_free_ref);

		orig_node_free_ref(orig_node);

	return len;

}

net/batman-adv/originator.c

+13 −8
Original line number Diff line number Diff line
@@ -102,13 +102,13 @@ struct neigh_node *create_neighbor(struct orig_node *orig_node, 
	return neigh_node;

}



void orig_node_free_ref(struct kref *refcount)

static void orig_node_free_rcu(struct rcu_head *rcu)

{

	struct hlist_node *node, *node_tmp;

	struct neigh_node *neigh_node, *tmp_neigh_node;

	struct orig_node *orig_node;



	orig_node = container_of(refcount, struct orig_node, refcount);

	orig_node = container_of(rcu, struct orig_node, rcu);



	spin_lock_bh(&orig_node->neigh_list_lock);
@@ -137,6 +137,12 @@ void orig_node_free_ref(struct kref *refcount) 
	kfree(orig_node);

}



void orig_node_free_ref(struct orig_node *orig_node)

{

	if (atomic_dec_and_test(&orig_node->refcount))

		call_rcu(&orig_node->rcu, orig_node_free_rcu);

}



void originator_free(struct bat_priv *bat_priv)

{

	struct hashtable_t *hash = bat_priv->orig_hash;
@@ -163,7 +169,7 @@ void originator_free(struct bat_priv *bat_priv) 
					  head, hash_entry) {



			hlist_del_rcu(node);

			kref_put(&orig_node->refcount, orig_node_free_ref);

			orig_node_free_ref(orig_node);

		}

		spin_unlock_bh(list_lock);

	}
@@ -196,7 +202,9 @@ struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr) 
	spin_lock_init(&orig_node->ogm_cnt_lock);

	spin_lock_init(&orig_node->bcast_seqno_lock);

	spin_lock_init(&orig_node->neigh_list_lock);

	kref_init(&orig_node->refcount);



	/* extra reference for return */

	atomic_set(&orig_node->refcount, 2);



	orig_node->bat_priv = bat_priv;

	memcpy(orig_node->orig, addr, ETH_ALEN);
@@ -229,8 +237,6 @@ struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr) 
	if (hash_added < 0)

		goto free_bcast_own_sum;



	/* extra reference for return */

	kref_get(&orig_node->refcount);

	return orig_node;

free_bcast_own_sum:

	kfree(orig_node->bcast_own_sum);
@@ -348,8 +354,7 @@ static void _purge_orig(struct bat_priv *bat_priv) 
				if (orig_node->gw_flags)

					gw_node_delete(bat_priv, orig_node);

				hlist_del_rcu(node);

				kref_put(&orig_node->refcount,

					 orig_node_free_ref);

				orig_node_free_ref(orig_node);

				continue;

			}

net/batman-adv/originator.h

+4 −2
Original line number Diff line number Diff line
@@ -27,7 +27,7 @@ 
int originator_init(struct bat_priv *bat_priv);

void originator_free(struct bat_priv *bat_priv);

void purge_orig_ref(struct bat_priv *bat_priv);

void orig_node_free_ref(struct kref *refcount);

void orig_node_free_ref(struct orig_node *orig_node);

struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr);

struct neigh_node *create_neighbor(struct orig_node *orig_node,

				   struct orig_node *orig_neigh_node,
@@ -88,8 +88,10 @@ static inline struct orig_node *orig_hash_find(struct bat_priv *bat_priv, 
		if (!compare_eth(orig_node, data))

			continue;



		if (!atomic_inc_not_zero(&orig_node->refcount))

			continue;



		orig_node_tmp = orig_node;

		kref_get(&orig_node_tmp->refcount);

		break;

	}

	rcu_read_unlock();

net/batman-adv/routing.c

+12 −12
Original line number Diff line number Diff line
@@ -420,7 +420,7 @@ static void update_orig(struct bat_priv *bat_priv, 
		neigh_node = create_neighbor(orig_node, orig_tmp,

					     ethhdr->h_source, if_incoming);



		kref_put(&orig_tmp->refcount, orig_node_free_ref);

		orig_node_free_ref(orig_tmp);

		if (!neigh_node)

			goto unlock;
@@ -604,7 +604,7 @@ static char count_real_packets(struct ethhdr *ethhdr, 


out:

	spin_unlock_bh(&orig_node->ogm_cnt_lock);

	kref_put(&orig_node->refcount, orig_node_free_ref);

	orig_node_free_ref(orig_node);

	return ret;

}
@@ -730,7 +730,7 @@ void receive_bat_packet(struct ethhdr *ethhdr, 


		bat_dbg(DBG_BATMAN, bat_priv, "Drop packet: "

			"originator packet from myself (via neighbor)\n");

		kref_put(&orig_neigh_node->refcount, orig_node_free_ref);

		orig_node_free_ref(orig_neigh_node);

		return;

	}
@@ -835,10 +835,10 @@ void receive_bat_packet(struct ethhdr *ethhdr, 
				0, hna_buff_len, if_incoming);



out_neigh:

	if (!is_single_hop_neigh)

		kref_put(&orig_neigh_node->refcount, orig_node_free_ref);

	if ((orig_neigh_node) && (!is_single_hop_neigh))

		orig_node_free_ref(orig_neigh_node);

out:

	kref_put(&orig_node->refcount, orig_node_free_ref);

	orig_node_free_ref(orig_node);

}



int recv_bat_packet(struct sk_buff *skb, struct batman_if *batman_if)
@@ -952,7 +952,7 @@ out: 
	if (neigh_node)

		neigh_node_free_ref(neigh_node);

	if (orig_node)

		kref_put(&orig_node->refcount, orig_node_free_ref);

		orig_node_free_ref(orig_node);

	return ret;

}
@@ -1028,7 +1028,7 @@ out: 
	if (neigh_node)

		neigh_node_free_ref(neigh_node);

	if (orig_node)

		kref_put(&orig_node->refcount, orig_node_free_ref);

		orig_node_free_ref(orig_node);

	return ret;

}
@@ -1134,7 +1134,7 @@ out: 
	if (neigh_node)

		neigh_node_free_ref(neigh_node);

	if (orig_node)

		kref_put(&orig_node->refcount, orig_node_free_ref);

		orig_node_free_ref(orig_node);

	return ret;

}
@@ -1189,7 +1189,7 @@ struct neigh_node *find_router(struct bat_priv *bat_priv, 
		if (!primary_orig_node)

			goto return_router;



		kref_put(&primary_orig_node->refcount, orig_node_free_ref);

		orig_node_free_ref(primary_orig_node);

	}



	/* with less than 2 candidates, we can't do any
@@ -1401,7 +1401,7 @@ out: 
	if (neigh_node)

		neigh_node_free_ref(neigh_node);

	if (orig_node)

		kref_put(&orig_node->refcount, orig_node_free_ref);

		orig_node_free_ref(orig_node);

	return ret;

}
@@ -1543,7 +1543,7 @@ spin_unlock: 
	spin_unlock_bh(&bat_priv->orig_hash_lock);

out:

	if (orig_node)

		kref_put(&orig_node->refcount, orig_node_free_ref);

		orig_node_free_ref(orig_node);

	return ret;

}

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