From mboxrd@z Thu Jan 1 00:00:00 1970 From: Elena Reshetova Date: Fri, 20 Oct 2017 07:23:44 +0000 Subject: [PATCH 10/15] drivers, net: convert masces_rx_sc.refcnt from atomic_t to refcount_t Message-Id: <1508484229-19706-11-git-send-email-elena.reshetova@intel.com> List-Id: References: <1508484229-19706-1-git-send-email-elena.reshetova@intel.com> In-Reply-To: <1508484229-19706-1-git-send-email-elena.reshetova@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: davem@davemloft.net Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-rdma@vger.kernel.org, linux-hams@vger.kernel.org, linux-ppp@vger.kernel.org, ganeshgr@chelsio.com, nbd@openwrt.org, john@phrozen.org, sean.wang@mediatek.com, matthias.bgg@gmail.com, yishaih@mellanox.com, saeedm@mellanox.com, matanb@mellanox.com, tariqt@mellanox.com, leonro@mellanox.com, ajk@comnets.uni-bremen.de, paulus@samba.org, zbr@ioremap.net, peterz@infradead.org, keescook@chromium.org, Elena Reshetova 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 Reviewed-by: David Windsor Reviewed-by: Hans Liljestrand Signed-off-by: Elena Reshetova --- 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); -- 2.7.4