Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 17ac99b2 authored by Elena Reshetova's avatar Elena Reshetova Committed by David S. Miller
Browse files

drivers, net, mlx4: convert mlx4_srq.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 mlx4_srq.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 0068895f
Loading
Loading
Loading
Loading
+4 −4
Original line number Diff line number Diff line
@@ -49,7 +49,7 @@ void mlx4_srq_event(struct mlx4_dev *dev, u32 srqn, int event_type)
	srq = radix_tree_lookup(&srq_table->tree, srqn & (dev->caps.num_srqs - 1));
	rcu_read_unlock();
	if (srq)
		atomic_inc(&srq->refcount);
		refcount_inc(&srq->refcount);
	else {
		mlx4_warn(dev, "Async event for bogus SRQ %08x\n", srqn);
		return;
@@ -57,7 +57,7 @@ void mlx4_srq_event(struct mlx4_dev *dev, u32 srqn, int event_type)

	srq->event(srq, event_type);

	if (atomic_dec_and_test(&srq->refcount))
	if (refcount_dec_and_test(&srq->refcount))
		complete(&srq->free);
}

@@ -203,7 +203,7 @@ int mlx4_srq_alloc(struct mlx4_dev *dev, u32 pdn, u32 cqn, u16 xrcd,
	if (err)
		goto err_radix;

	atomic_set(&srq->refcount, 1);
	refcount_set(&srq->refcount, 1);
	init_completion(&srq->free);

	return 0;
@@ -232,7 +232,7 @@ void mlx4_srq_free(struct mlx4_dev *dev, struct mlx4_srq *srq)
	radix_tree_delete(&srq_table->tree, srq->srqn);
	spin_unlock_irq(&srq_table->lock);

	if (atomic_dec_and_test(&srq->refcount))
	if (refcount_dec_and_test(&srq->refcount))
		complete(&srq->free);
	wait_for_completion(&srq->free);

+1 −1
Original line number Diff line number Diff line
@@ -781,7 +781,7 @@ struct mlx4_srq {
	int			max_gs;
	int			wqe_shift;

	atomic_t		refcount;
	refcount_t		refcount;
	struct completion	free;
};