refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations.
Signed-off-by: Elena Reshetova <[email protected]> Signed-off-by: Hans Liljestrand <[email protected]> Signed-off-by: Kees Cook <[email protected]> Signed-off-by: David Windsor <[email protected]> --- net/netfilter/nfnetlink_log.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c index 08247bf..ecd857b 100644 --- a/net/netfilter/nfnetlink_log.c +++ b/net/netfilter/nfnetlink_log.c @@ -40,6 +40,8 @@ #include <net/netfilter/nfnetlink_log.h> #include <linux/atomic.h> +#include <linux/refcount.h> + #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) #include "../bridge/br_private.h" @@ -57,7 +59,7 @@ struct nfulnl_instance { struct hlist_node hlist; /* global list of instances */ spinlock_t lock; - atomic_t use; /* use count */ + refcount_t use; /* use count */ unsigned int qlen; /* number of nlmsgs in skb */ struct sk_buff *skb; /* pre-allocatd skb */ @@ -115,7 +117,7 @@ __instance_lookup(struct nfnl_log_net *log, u_int16_t group_num) static inline void instance_get(struct nfulnl_instance *inst) { - atomic_inc(&inst->use); + refcount_inc(&inst->use); } static struct nfulnl_instance * @@ -125,7 +127,7 @@ instance_lookup_get(struct nfnl_log_net *log, u_int16_t group_num) rcu_read_lock_bh(); inst = __instance_lookup(log, group_num); - if (inst && !atomic_inc_not_zero(&inst->use)) + if (inst && !refcount_inc_not_zero(&inst->use)) inst = NULL; rcu_read_unlock_bh(); @@ -145,7 +147,7 @@ static void nfulnl_instance_free_rcu(struct rcu_head *head) static void instance_put(struct nfulnl_instance *inst) { - if (inst && atomic_dec_and_test(&inst->use)) + if (inst && refcount_dec_and_test(&inst->use)) call_rcu_bh(&inst->rcu, nfulnl_instance_free_rcu); } @@ -180,7 +182,7 @@ instance_create(struct net *net, u_int16_t group_num, INIT_HLIST_NODE(&inst->hlist); spin_lock_init(&inst->lock); /* needs to be two, since we _put() after creation */ - atomic_set(&inst->use, 2); + refcount_set(&inst->use, 2); setup_timer(&inst->timer, nfulnl_timer, (unsigned long)inst); @@ -1031,7 +1033,7 @@ static int seq_show(struct seq_file *s, void *v) inst->group_num, inst->peer_portid, inst->qlen, inst->copy_mode, inst->copy_range, - inst->flushtimeout, atomic_read(&inst->use)); + inst->flushtimeout, refcount_read(&inst->use)); return 0; } -- 2.7.4
