drivers, net, mlx5: convert mlx5_cq.refcount 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 mlx5_cq.refcount 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>
diff --git a/include/linux/mlx5/cq.h b/include/linux/mlx5/cq.h
index 9589884..6a57ec2 100644
--- a/include/linux/mlx5/cq.h
+++ b/include/linux/mlx5/cq.h
@@ -35,7 +35,7 @@
#include <rdma/ib_verbs.h>
#include <linux/mlx5/driver.h>
-
+#include <linux/refcount.h>
struct mlx5_core_cq {
u32 cqn;
@@ -43,7 +43,7 @@ struct mlx5_core_cq {
__be32 *set_ci_db;
__be32 *arm_db;
struct mlx5_uars_page *uar;
- atomic_t refcount;
+ refcount_t refcount;
struct completion free;
unsigned vector;
unsigned int irqn;