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

Elena Reshetova
2017-03-06T14:21:07Z

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@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.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

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