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.reshet...@intel.com>
Signed-off-by: Hans Liljestrand <ishkam...@gmail.com>
Signed-off-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: David Windsor <dwind...@gmail.com>
---
 net/rds/ib.c      | 12 ++++++------
 net/rds/ib.h      |  2 +-
 net/rds/ib_rdma.c |  4 ++--
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/net/rds/ib.c b/net/rds/ib.c
index 91fe46f..bb19cda 100644
--- a/net/rds/ib.c
+++ b/net/rds/ib.c
@@ -118,8 +118,8 @@ static void rds_ib_dev_free(struct work_struct *work)
 
 void rds_ib_dev_put(struct rds_ib_device *rds_ibdev)
 {
-       BUG_ON(atomic_read(&rds_ibdev->refcount) <= 0);
-       if (atomic_dec_and_test(&rds_ibdev->refcount))
+       BUG_ON(refcount_read(&rds_ibdev->refcount) == 0);
+       if (refcount_dec_and_test(&rds_ibdev->refcount))
                queue_work(rds_wq, &rds_ibdev->free_work);
 }
 
@@ -137,7 +137,7 @@ static void rds_ib_add_one(struct ib_device *device)
                return;
 
        spin_lock_init(&rds_ibdev->spinlock);
-       atomic_set(&rds_ibdev->refcount, 1);
+       refcount_set(&rds_ibdev->refcount, 1);
        INIT_WORK(&rds_ibdev->free_work, rds_ib_dev_free);
 
        rds_ibdev->max_wrs = device->attrs.max_qp_wr;
@@ -205,10 +205,10 @@ static void rds_ib_add_one(struct ib_device *device)
        down_write(&rds_ib_devices_lock);
        list_add_tail_rcu(&rds_ibdev->list, &rds_ib_devices);
        up_write(&rds_ib_devices_lock);
-       atomic_inc(&rds_ibdev->refcount);
+       refcount_inc(&rds_ibdev->refcount);
 
        ib_set_client_data(device, &rds_ib_client, rds_ibdev);
-       atomic_inc(&rds_ibdev->refcount);
+       refcount_inc(&rds_ibdev->refcount);
 
        rds_ib_nodev_connect();
 
@@ -239,7 +239,7 @@ struct rds_ib_device *rds_ib_get_client_data(struct 
ib_device *device)
        rcu_read_lock();
        rds_ibdev = ib_get_client_data(device, &rds_ib_client);
        if (rds_ibdev)
-               atomic_inc(&rds_ibdev->refcount);
+               refcount_inc(&rds_ibdev->refcount);
        rcu_read_unlock();
        return rds_ibdev;
 }
diff --git a/net/rds/ib.h b/net/rds/ib.h
index ec55062..bf48224 100644
--- a/net/rds/ib.h
+++ b/net/rds/ib.h
@@ -230,7 +230,7 @@ struct rds_ib_device {
        unsigned int            max_initiator_depth;
        unsigned int            max_responder_resources;
        spinlock_t              spinlock;       /* protect the above */
-       atomic_t                refcount;
+       refcount_t              refcount;
        struct work_struct      free_work;
        int                     *vector_load;
 };
diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c
index 977f698..9a3c54e 100644
--- a/net/rds/ib_rdma.c
+++ b/net/rds/ib_rdma.c
@@ -52,7 +52,7 @@ static struct rds_ib_device *rds_ib_get_device(__be32 ipaddr)
        list_for_each_entry_rcu(rds_ibdev, &rds_ib_devices, list) {
                list_for_each_entry_rcu(i_ipaddr, &rds_ibdev->ipaddr_list, 
list) {
                        if (i_ipaddr->ipaddr == ipaddr) {
-                               atomic_inc(&rds_ibdev->refcount);
+                               refcount_inc(&rds_ibdev->refcount);
                                rcu_read_unlock();
                                return rds_ibdev;
                        }
@@ -134,7 +134,7 @@ void rds_ib_add_conn(struct rds_ib_device *rds_ibdev, 
struct rds_connection *con
        spin_unlock_irq(&ib_nodev_conns_lock);
 
        ic->rds_ibdev = rds_ibdev;
-       atomic_inc(&rds_ibdev->refcount);
+       refcount_inc(&rds_ibdev->refcount);
 }
 
 void rds_ib_remove_conn(struct rds_ib_device *rds_ibdev, struct rds_connection 
*conn)
-- 
2.7.4

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