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@xxxxxxxxxxxx>
Reviewed-by: David Windsor <dwindsor@xxxxxxxxx>
Reviewed-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
Signed-off-by: Elena Reshetova <elena.reshetova@xxxxxxxxx>
---
drivers/net/ethernet/mellanox/mlx5/core/cq.c | 16 ++++++++--------
include/linux/mlx5/cq.h | 4 ++--
2 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/cq.c b/drivers/net/ethernet/mellanox/mlx5/core/cq.c
index 336d473..1016e05 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/cq.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/cq.c
@@ -58,7 +58,7 @@ void mlx5_cq_tasklet_cb(unsigned long data)
tasklet_ctx.list) {
list_del_init(&mcq->tasklet_ctx.list);
mcq->tasklet_ctx.comp(mcq);
- if (atomic_dec_and_test(&mcq->refcount))
+ if (refcount_dec_and_test(&mcq->refcount))
complete(&mcq->free);
if (time_after(jiffies, end))
break;
@@ -80,7 +80,7 @@ static void mlx5_add_cq_to_tasklet(struct mlx5_core_cq *cq)
* still arrive.
*/
if (list_empty_careful(&cq->tasklet_ctx.list)) {
- atomic_inc(&cq->refcount);
+ refcount_inc(&cq->refcount);
list_add_tail(&cq->tasklet_ctx.list, &tasklet_ctx->list);
}
spin_unlock_irqrestore(&tasklet_ctx->lock, flags);
@@ -94,7 +94,7 @@ void mlx5_cq_completion(struct mlx5_core_dev *dev, u32 cqn)
spin_lock(&table->lock);
cq = radix_tree_lookup(&table->tree, cqn);
if (likely(cq))
- atomic_inc(&cq->refcount);
+ refcount_inc(&cq->refcount);
spin_unlock(&table->lock);
if (!cq) {
@@ -106,7 +106,7 @@ void mlx5_cq_completion(struct mlx5_core_dev *dev, u32 cqn)
cq->comp(cq);
- if (atomic_dec_and_test(&cq->refcount))
+ if (refcount_dec_and_test(&cq->refcount))
complete(&cq->free);
}
@@ -119,7 +119,7 @@ void mlx5_cq_event(struct mlx5_core_dev *dev, u32 cqn, int event_type)
cq = radix_tree_lookup(&table->tree, cqn);
if (cq)
- atomic_inc(&cq->refcount);
+ refcount_inc(&cq->refcount);
spin_unlock(&table->lock);
@@ -130,7 +130,7 @@ void mlx5_cq_event(struct mlx5_core_dev *dev, u32 cqn, int event_type)
cq->event(cq, event_type);
- if (atomic_dec_and_test(&cq->refcount))
+ if (refcount_dec_and_test(&cq->refcount))
complete(&cq->free);
}
@@ -159,7 +159,7 @@ int mlx5_core_create_cq(struct mlx5_core_dev *dev, struct mlx5_core_cq *cq,
cq->cqn = MLX5_GET(create_cq_out, out, cqn);
cq->cons_index = 0;
cq->arm_sn = 0;
- atomic_set(&cq->refcount, 1);
+ refcount_set(&cq->refcount, 1);
init_completion(&cq->free);
if (!cq->comp)
cq->comp = mlx5_add_cq_to_tasklet;
@@ -222,7 +222,7 @@ int mlx5_core_destroy_cq(struct mlx5_core_dev *dev, struct mlx5_core_cq *cq)
synchronize_irq(cq->irqn);
mlx5_debug_cq_remove(dev, cq);
- if (atomic_dec_and_test(&cq->refcount))
+ if (refcount_dec_and_test(&cq->refcount))
complete(&cq->free);
wait_for_completion(&cq->free);
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;
--
2.7.4
--
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