commit 60dff56d77292062789232f68354f567e1ccf1d2
author Weihang Li <liweihang@huawei.com> Fri May 28 17:37:32 2021 +0800
committer Jason Gunthorpe <jgg@nvidia.com> Tue Jun 08 14:35:44 2021 -0300
tree 5e8f23a28e3a832b086d6b3e0ff6beedf1dcf45d
parent 61c7d826b81769ea57d094305c900f903768f322

RDMA/core: Use refcount_t instead of atomic_t on refcount of iwcm_id_private

The refcount_t API will WARN on underflow and overflow of a reference
counter, and avoid use-after-free risks.

Link: https://lore.kernel.org/r/1622194663-2383-2-git-send-email-liweihang@huawei.com
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/iwcm.c

diff --git a/drivers/infiniband/core/iwcm.c b/drivers/infiniband/core/iwcm.c
index da8adad..4226115 100644
--- a/drivers/infiniband/core/iwcm.c
+++ b/drivers/infiniband/core/iwcm.c
@@ -211,8 +211,7 @@ static void free_cm_id(struct iwcm_id_private *cm_id_priv)
  */
 static int iwcm_deref_id(struct iwcm_id_private *cm_id_priv)
 {
-	BUG_ON(atomic_read(&cm_id_priv->refcount)==0);
-	if (atomic_dec_and_test(&cm_id_priv->refcount)) {
+	if (refcount_dec_and_test(&cm_id_priv->refcount)) {
 		BUG_ON(!list_empty(&cm_id_priv->work_list));
 		free_cm_id(cm_id_priv);
 		return 1;
@@ -225,7 +224,7 @@ static void add_ref(struct iw_cm_id *cm_id)
 {
 	struct iwcm_id_private *cm_id_priv;
 	cm_id_priv = container_of(cm_id, struct iwcm_id_private, id);
-	atomic_inc(&cm_id_priv->refcount);
+	refcount_inc(&cm_id_priv->refcount);
 }
 
 static void rem_ref(struct iw_cm_id *cm_id)
@@ -257,7 +256,7 @@ struct iw_cm_id *iw_create_cm_id(struct ib_device *device,
 	cm_id_priv->id.add_ref = add_ref;
 	cm_id_priv->id.rem_ref = rem_ref;
 	spin_lock_init(&cm_id_priv->lock);
-	atomic_set(&cm_id_priv->refcount, 1);
+	refcount_set(&cm_id_priv->refcount, 1);
 	init_waitqueue_head(&cm_id_priv->connect_wait);
 	init_completion(&cm_id_priv->destroy_comp);
 	INIT_LIST_HEAD(&cm_id_priv->work_list);
@@ -1094,7 +1093,7 @@ static int cm_event_handler(struct iw_cm_id *cm_id,
 		}
 	}
 
-	atomic_inc(&cm_id_priv->refcount);
+	refcount_inc(&cm_id_priv->refcount);
 	if (list_empty(&cm_id_priv->work_list)) {
 		list_add_tail(&work->list, &cm_id_priv->work_list);
 		queue_work(iwcm_wq, &work->work);

drivers/infiniband/core/iwcm.h

diff --git a/drivers/infiniband/core/iwcm.h b/drivers/infiniband/core/iwcm.h
index 82c2cd1..bf74639 100644
--- a/drivers/infiniband/core/iwcm.h
+++ b/drivers/infiniband/core/iwcm.h
@@ -52,7 +52,7 @@ struct iwcm_id_private {
 	wait_queue_head_t connect_wait;
 	struct list_head work_list;
 	spinlock_t lock;
-	atomic_t refcount;
+	refcount_t refcount;
 	struct list_head work_free_list;
 };