diff options
authorElena Reshetova <elena.reshetova@intel.com>2017-10-20 10:23:49 +0300
committerDavid S. Miller <davem@davemloft.net>2017-10-22 02:22:39 +0100
commite65f7ee39b4d7604a78b03ed35d723e1001fc241 (patch)
parent709c89b45b874b2f81a074b8802a736009873f48 (diff)
drivers, connector: convert cn_callback_entry.refcnt from atomic_t to refcount_t
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 <keescook@chromium.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
3 files changed, 5 insertions, 5 deletions
diff --git a/drivers/connector/cn_queue.c b/drivers/connector/cn_queue.c
index 1f8bf054d11c..9c54fdf7acea 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);
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))
diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c
index 25693b045371..8615594bd065 100644
--- a/drivers/connector/connector.c
+++ b/drivers/connector/connector.c
@@ -157,7 +157,7 @@ static int cn_call_callback(struct sk_buff *skb)
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;
diff --git a/include/linux/connector.h b/include/linux/connector.h
index f8fe8637d771..032102b19645 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;

Privacy Policy