[PATCH 15/15] drivers, connector: convert cn_callback_entry.refcnt from atomic_t to refcount_t
From: elena.reshetova@intel.com (Elena Reshetova)
Date: 2017-10-20 07:25:56
Also in:
linux-hams, linux-mediatek, linux-rdma, lkml, netdev
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable cn_callback_entry.refcnt is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook <redacted> Reviewed-by: David Windsor <redacted> Reviewed-by: Hans Liljestrand <redacted> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> --- drivers/connector/cn_queue.c | 4 ++-- drivers/connector/connector.c | 2 +- include/linux/connector.h | 4 ++-- 3 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/connector/cn_queue.c b/drivers/connector/cn_queue.c
index 1f8bf05..9c54fdf 100644
--- a/drivers/connector/cn_queue.c
+++ b/drivers/connector/cn_queue.c@@ -45,7 +45,7 @@ cn_queue_alloc_callback_entry(struct cn_queue_dev *dev, const char *name, return NULL; } - atomic_set(&cbq->refcnt, 1); + refcount_set(&cbq->refcnt, 1); atomic_inc(&dev->refcnt); cbq->pdev = dev;
@@ -58,7 +58,7 @@ cn_queue_alloc_callback_entry(struct cn_queue_dev *dev, const char *name, void cn_queue_release_callback(struct cn_callback_entry *cbq) { - if (!atomic_dec_and_test(&cbq->refcnt)) + if (!refcount_dec_and_test(&cbq->refcnt)) return; atomic_dec(&cbq->pdev->refcnt);
diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c
index 25693b0..8615594b 100644
--- a/drivers/connector/connector.c
+++ b/drivers/connector/connector.c@@ -157,7 +157,7 @@ static int cn_call_callback(struct sk_buff *skb) spin_lock_bh(&dev->cbdev->queue_lock); list_for_each_entry(i, &dev->cbdev->queue_list, callback_entry) { if (cn_cb_equal(&i->id.id, &msg->id)) { - atomic_inc(&i->refcnt); + refcount_inc(&i->refcnt); cbq = i; break; }
diff --git a/include/linux/connector.h b/include/linux/connector.h
index f8fe863..032102b 100644
--- a/include/linux/connector.h
+++ b/include/linux/connector.h@@ -22,7 +22,7 @@ #define __CONNECTOR_H -#include <linux/atomic.h> +#include <linux/refcount.h> #include <linux/list.h> #include <linux/workqueue.h>
@@ -49,7 +49,7 @@ struct cn_callback_id { struct cn_callback_entry { struct list_head callback_entry; - atomic_t refcnt; + refcount_t refcnt; struct cn_queue_dev *pdev; struct cn_callback_id id;
--
2.7.4