netdev - [PATCH 08/18] net, atm: convert lec_arp_table.usage from atomic_t to refcount

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Message-Id: <1489749179-12063-9-git-send-email-elena.reshetova@intel.com>
Date:   Fri, 17 Mar 2017 13:12:49 +0200
From:   Elena Reshetova <elena.reshetova@...el.com>
To:     netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        linux-decnet-user@...ts.sourceforge.net, davem@...emloft.net,
        jmorris@...ei.org, kaber@...sh.net, yoshfuji@...ux-ipv6.org,
        kuznet@....inr.ac.ru, 3chas3@...il.com, ralf@...ux-mips.org,
        stephen@...workplumber.org, jchapman@...alix.com, jhs@...atatu.com,
        bridge@...ts.linux-foundation.org, linux-hams@...r.kernel.org,
        linux-x25@...r.kernel.org, linux-bluetooth@...r.kernel.org,
        marcel@...tmann.org, johan.hedberg@...il.com, peterz@...radead.org,
        keescook@...omium.org, Elena Reshetova <elena.reshetova@...el.com>,
        Hans Liljestrand <ishkamiel@...il.com>,
        David Windsor <dwindsor@...il.com>
Subject: [PATCH 08/18] net, atm: convert lec_arp_table.usage from atomic_t to refcount_t

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 <elena.reshetova@...el.com>
Signed-off-by: Hans Liljestrand <ishkamiel@...il.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: David Windsor <dwindsor@...il.com>
---
 net/atm/lec.c      | 6 +++---
 net/atm/lec_arpc.h | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/atm/lec.c b/net/atm/lec.c
index 09cfe87..431f32c 100644
--- a/net/atm/lec.c
+++ b/net/atm/lec.c
@@ -101,12 +101,12 @@ static void lec_vcc_close(struct lec_priv *priv, struct atm_vcc *vcc);
 /* must be done under lec_arp_lock */
 static inline void lec_arp_hold(struct lec_arp_table *entry)
 {
-	atomic_inc(&entry->usage);
+	refcount_inc(&entry->usage);
 }
 
 static inline void lec_arp_put(struct lec_arp_table *entry)
 {
-	if (atomic_dec_and_test(&entry->usage))
+	if (refcount_dec_and_test(&entry->usage))
 		kfree(entry);
 }
 
@@ -1564,7 +1564,7 @@ static struct lec_arp_table *make_entry(struct lec_priv *priv,
 	to_return->last_used = jiffies;
 	to_return->priv = priv;
 	skb_queue_head_init(&to_return->tx_wait);
-	atomic_set(&to_return->usage, 1);
+	refcount_set(&to_return->usage, 1);
 	return to_return;
 }
 
diff --git a/net/atm/lec_arpc.h b/net/atm/lec_arpc.h
index ec67435..d923f53 100644
--- a/net/atm/lec_arpc.h
+++ b/net/atm/lec_arpc.h
@@ -47,7 +47,7 @@ struct lec_arp_table {
 					 * the length of the tlvs array
 					 */
 	struct sk_buff_head tx_wait;	/* wait queue for outgoing packets */
-	atomic_t usage;			/* usage count */
+	refcount_t usage;		/* usage count */
 };
 
 /*
-- 
2.7.4