From e187246f0f7522e306d1d156a2d5edcaf82ba840 Mon Sep 17 00:00:00 2001 From: Elena Reshetova Date: Fri, 20 Oct 2017 10:23:43 +0300 Subject: drivers, net: convert masces_rx_sa.refcnt from atomic_t to refcount_t atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable masces_rx_sa.refcnt is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook Reviewed-by: David Windsor Reviewed-by: Hans Liljestrand Signed-off-by: Elena Reshetova Signed-off-by: David S. Miller --- drivers/net/macsec.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'drivers/net/macsec.c') diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c index ccbe4eaffe4d..733e1c240bf5 100644 --- a/drivers/net/macsec.c +++ b/drivers/net/macsec.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -146,7 +147,7 @@ struct macsec_rx_sa { struct macsec_key key; spinlock_t lock; u32 next_pn; - atomic_t refcnt; + refcount_t refcnt; bool active; struct macsec_rx_sa_stats __percpu *stats; struct macsec_rx_sc *sc; @@ -314,7 +315,7 @@ static struct macsec_rx_sa *macsec_rxsa_get(struct macsec_rx_sa __rcu *ptr) if (!sa || !sa->active) return NULL; - if (!atomic_inc_not_zero(&sa->refcnt)) + if (!refcount_inc_not_zero(&sa->refcnt)) return NULL; return sa; @@ -350,7 +351,7 @@ static void free_rxsa(struct rcu_head *head) static void macsec_rxsa_put(struct macsec_rx_sa *sa) { - if (atomic_dec_and_test(&sa->refcnt)) + if (refcount_dec_and_test(&sa->refcnt)) call_rcu(&sa->rcu, free_rxsa); } @@ -1339,7 +1340,7 @@ static int init_rx_sa(struct macsec_rx_sa *rx_sa, char *sak, int key_len, rx_sa->active = false; rx_sa->next_pn = 1; - atomic_set(&rx_sa->refcnt, 1); + refcount_set(&rx_sa->refcnt, 1); spin_lock_init(&rx_sa->lock); return 0; -- cgit v1.2.3-59-g8ed1b