netdev - [PATCH 20/29] drivers, s390: convert qeth_reply.refcnt from atomic_t to refcount

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Message-Id: <1488810076-3754-21-git-send-email-elena.reshetova@intel.com>
Date:   Mon,  6 Mar 2017 16:21:07 +0200
From:   Elena Reshetova <elena.reshetova@...el.com>
To:     gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
        netdev@...r.kernel.org, linux1394-devel@...ts.sourceforge.net,
        linux-bcache@...r.kernel.org, linux-raid@...r.kernel.org,
        linux-media@...r.kernel.org, devel@...uxdriverproject.org,
        linux-pci@...r.kernel.org, linux-s390@...r.kernel.org,
        fcoe-devel@...n-fcoe.org, linux-scsi@...r.kernel.org,
        open-iscsi@...glegroups.com, devel@...verdev.osuosl.org,
        target-devel@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-usb@...r.kernel.org, peterz@...radead.org,
        Elena Reshetova <elena.reshetova@...el.com>,
        Hans Liljestrand <ishkamiel@...il.com>,
        Kees Cook <keescook@...omium.org>,
        David Windsor <dwindsor@...il.com>
Subject: [PATCH 20/29] drivers, s390: convert qeth_reply.refcnt 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>
---
 drivers/s390/net/qeth_core.h      | 3 ++-
 drivers/s390/net/qeth_core_main.c | 8 +++-----
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h
index e7addea..e2c81d21 100644
--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -20,6 +20,7 @@
 #include <linux/ethtool.h>
 #include <linux/hashtable.h>
 #include <linux/ip.h>
+#include <linux/refcount.h>
 
 #include <net/ipv6.h>
 #include <net/if_inet6.h>
@@ -641,7 +642,7 @@ struct qeth_reply {
 	int rc;
 	void *param;
 	struct qeth_card *card;
-	atomic_t refcnt;
+	refcount_t refcnt;
 };
 
 
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 315d8a2..a2bf13f 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -555,7 +555,7 @@ static struct qeth_reply *qeth_alloc_reply(struct qeth_card *card)
 
 	reply = kzalloc(sizeof(struct qeth_reply), GFP_ATOMIC);
 	if (reply) {
-		atomic_set(&reply->refcnt, 1);
+		refcount_set(&reply->refcnt, 1);
 		atomic_set(&reply->received, 0);
 		reply->card = card;
 	}
@@ -564,14 +564,12 @@ static struct qeth_reply *qeth_alloc_reply(struct qeth_card *card)
 
 static void qeth_get_reply(struct qeth_reply *reply)
 {
-	WARN_ON(atomic_read(&reply->refcnt) <= 0);
-	atomic_inc(&reply->refcnt);
+	refcount_inc(&reply->refcnt);
 }
 
 static void qeth_put_reply(struct qeth_reply *reply)
 {
-	WARN_ON(atomic_read(&reply->refcnt) <= 0);
-	if (atomic_dec_and_test(&reply->refcnt))
+	if (refcount_dec_and_test(&reply->refcnt))
 		kfree(reply);
 }
 
-- 
2.7.4