diff options
| author | Elena Reshetova <elena.reshetova@intel.com> | 2017-10-20 10:23:49 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-10-22 02:22:39 +0100 |
| commit | e65f7ee39b4d7604a78b03ed35d723e1001fc241 (patch) | |
| tree | 047ba8c6ba1f159c9339923ca939dbb2d81c5897 | |
| parent | 709c89b45b874b2f81a074b8802a736009873f48 (diff) | |
| download | linux-e65f7ee39b4d7604a78b03ed35d723e1001fc241.tar.bz2 | |
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>
| -rw-r--r-- | drivers/connector/cn_queue.c | 4 | ||||
| -rw-r--r-- | drivers/connector/connector.c | 2 | ||||
| -rw-r--r-- | 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 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); 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 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) 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 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; |