[PATCH 10/15] drivers, net: convert masces_rx_sc.refcnt from atomic_t to refcount_t

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


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_sc.refcnt is used as pure reference counter.
Convert it to refcount_t and fix up the operations.

Suggested-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: David Windsor <dwindsor@xxxxxxxxx>
Reviewed-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
Signed-off-by: Elena Reshetova <elena.reshetova@xxxxxxxxx>
 drivers/net/macsec.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
index 733e1c2..e0aeb51 100644
--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -172,7 +172,7 @@ struct macsec_rx_sc {
 	bool active;
 	struct macsec_rx_sa __rcu *sa[MACSEC_NUM_AN];
 	struct pcpu_rx_sc_stats __percpu *stats;
-	atomic_t refcnt;
+	refcount_t refcnt;
 	struct rcu_head rcu_head;
@@ -331,12 +331,12 @@ static void free_rx_sc_rcu(struct rcu_head *head)
 static struct macsec_rx_sc *macsec_rxsc_get(struct macsec_rx_sc *sc)
-	return atomic_inc_not_zero(&sc->refcnt) ? sc : NULL;
+	return refcount_inc_not_zero(&sc->refcnt) ? sc : NULL;
 static void macsec_rxsc_put(struct macsec_rx_sc *sc)
-	if (atomic_dec_and_test(&sc->refcnt))
+	if (refcount_dec_and_test(&sc->refcnt))
 		call_rcu(&sc->rcu_head, free_rx_sc_rcu);
@@ -1411,7 +1411,7 @@ static struct macsec_rx_sc *create_rx_sc(struct net_device *dev, sci_t sci)
 	rx_sc->sci = sci;
 	rx_sc->active = true;
-	atomic_set(&rx_sc->refcnt, 1);
+	refcount_set(&rx_sc->refcnt, 1);
 	secy = &macsec_priv(dev)->secy;
 	rcu_assign_pointer(rx_sc->next, secy->rx_sc);

To unsubscribe from this list: send the line "unsubscribe linux-ppp" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Index of Archives]     [Linux Audio Users]     [Linux for Hams]     [Kernel Newbies]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Video 4 Linux]     [Fedora Users]

  Powered by Linux