From mboxrd@z Thu Jan 1 00:00:00 1970 From: Elena Reshetova Date: Fri, 20 Oct 2017 07:23:45 +0000 Subject: [PATCH 11/15] drivers, net: convert masces_tx_sa.refcnt from atomic_t to refcount_t Message-Id: <1508484229-19706-12-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_tx_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 --- 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 e0aeb51..8948b6a 100644 --- a/drivers/net/macsec.c +++ b/drivers/net/macsec.c @@ -188,7 +188,7 @@ struct macsec_tx_sa { struct macsec_key key; spinlock_t lock; u32 next_pn; - atomic_t refcnt; + refcount_t refcnt; bool active; struct macsec_tx_sa_stats __percpu *stats; struct rcu_head rcu; @@ -362,7 +362,7 @@ static struct macsec_tx_sa *macsec_txsa_get(struct macsec_tx_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; @@ -379,7 +379,7 @@ static void free_txsa(struct rcu_head *head) static void macsec_txsa_put(struct macsec_tx_sa *sa) { - if (atomic_dec_and_test(&sa->refcnt)) + if (refcount_dec_and_test(&sa->refcnt)) call_rcu(&sa->rcu, free_txsa); } @@ -1437,7 +1437,7 @@ static int init_tx_sa(struct macsec_tx_sa *tx_sa, char *sak, int key_len, } tx_sa->active = false; - atomic_set(&tx_sa->refcnt, 1); + refcount_set(&tx_sa->refcnt, 1); spin_lock_init(&tx_sa->lock); return 0; -- 2.7.4