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Commit a4b51a9f authored by Elena Reshetova's avatar Elena Reshetova Committed by David S. Miller
Browse files

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: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarDavid Windsor <dwindsor@gmail.com>
Reviewed-by: default avatarHans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: default avatarElena Reshetova <elena.reshetova@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 17ac99b2

drivers/net/ethernet/mellanox/mlx5/core/cq.c

+8 −8
Original line number Diff line number Diff line
@@ -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);

include/linux/mlx5/cq.h

+2 −2
Original line number Diff line number Diff line
@@ -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;