netdev - [PATCH 09/18] net, atm: convert in_cache_entry.use from atomic_t to refcount

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Date:   Fri, 17 Mar 2017 13:12:50 +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 09/18] net, atm: convert in_cache_entry.use 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/mpoa_caches.c | 12 ++++++------
 net/atm/mpoa_caches.h |  3 ++-
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/net/atm/mpoa_caches.c b/net/atm/mpoa_caches.c
index a89fdeb..05e89e9 100644
--- a/net/atm/mpoa_caches.c
+++ b/net/atm/mpoa_caches.c
@@ -40,7 +40,7 @@ static in_cache_entry *in_cache_get(__be32 dst_ip,
 	entry = client->in_cache;
 	while (entry != NULL) {
 		if (entry->ctrl_info.in_dst_ip == dst_ip) {
-			atomic_inc(&entry->use);
+			refcount_inc(&entry->use);
 			read_unlock_bh(&client->ingress_lock);
 			return entry;
 		}
@@ -61,7 +61,7 @@ static in_cache_entry *in_cache_get_with_mask(__be32 dst_ip,
 	entry = client->in_cache;
 	while (entry != NULL) {
 		if ((entry->ctrl_info.in_dst_ip & mask) == (dst_ip & mask)) {
-			atomic_inc(&entry->use);
+			refcount_inc(&entry->use);
 			read_unlock_bh(&client->ingress_lock);
 			return entry;
 		}
@@ -82,7 +82,7 @@ static in_cache_entry *in_cache_get_by_vcc(struct atm_vcc *vcc,
 	entry = client->in_cache;
 	while (entry != NULL) {
 		if (entry->shortcut == vcc) {
-			atomic_inc(&entry->use);
+			refcount_inc(&entry->use);
 			read_unlock_bh(&client->ingress_lock);
 			return entry;
 		}
@@ -105,7 +105,7 @@ static in_cache_entry *in_cache_add_entry(__be32 dst_ip,
 
 	dprintk("adding an ingress entry, ip = %pI4\n", &dst_ip);
 
-	atomic_set(&entry->use, 1);
+	refcount_set(&entry->use, 1);
 	dprintk("new_in_cache_entry: about to lock\n");
 	write_lock_bh(&client->ingress_lock);
 	entry->next = client->in_cache;
@@ -121,7 +121,7 @@ static in_cache_entry *in_cache_add_entry(__be32 dst_ip,
 	entry->count = 1;
 	entry->entry_state = INGRESS_INVALID;
 	entry->ctrl_info.holding_time = HOLDING_TIME_DEFAULT;
-	atomic_inc(&entry->use);
+	refcount_inc(&entry->use);
 
 	write_unlock_bh(&client->ingress_lock);
 	dprintk("new_in_cache_entry: unlocked\n");
@@ -178,7 +178,7 @@ static int cache_hit(in_cache_entry *entry, struct mpoa_client *mpc)
 
 static void in_cache_put(in_cache_entry *entry)
 {
-	if (atomic_dec_and_test(&entry->use)) {
+	if (refcount_dec_and_test(&entry->use)) {
 		memset(entry, 0, sizeof(in_cache_entry));
 		kfree(entry);
 	}
diff --git a/net/atm/mpoa_caches.h b/net/atm/mpoa_caches.h
index 8e5f78c..38a4e7e 100644
--- a/net/atm/mpoa_caches.h
+++ b/net/atm/mpoa_caches.h
@@ -6,6 +6,7 @@
 #include <linux/atm.h>
 #include <linux/atmdev.h>
 #include <linux/atmmpc.h>
+#include <linux/refcount.h>
 
 struct mpoa_client;
 
@@ -25,7 +26,7 @@ typedef struct in_cache_entry {
 	struct   atm_vcc *shortcut;
 	uint8_t  MPS_ctrl_ATM_addr[ATM_ESA_LEN];
 	struct   in_ctrl_info ctrl_info;
-	atomic_t use;
+	refcount_t use;
 } in_cache_entry;
 
 struct in_cache_ops{
-- 
2.7.4