From 0068895ff845c38e9e2b65c002c53c623379e436 Mon Sep 17 00:00:00 2001 From: Elena Reshetova Date: Fri, 20 Oct 2017 10:23:38 +0300 Subject: [PATCH] drivers, net, mlx4: convert mlx4_qp.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_qp.refcount is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook Reviewed-by: David Windsor Reviewed-by: Hans Liljestrand Signed-off-by: Elena Reshetova Signed-off-by: David S. Miller --- drivers/net/ethernet/mellanox/mlx4/qp.c | 8 ++++---- include/linux/mlx4/device.h | 2 +- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx4/qp.c b/drivers/net/ethernet/mellanox/mlx4/qp.c index 2033209..769598f 100644 --- a/drivers/net/ethernet/mellanox/mlx4/qp.c +++ b/drivers/net/ethernet/mellanox/mlx4/qp.c @@ -55,7 +55,7 @@ void mlx4_qp_event(struct mlx4_dev *dev, u32 qpn, int event_type) qp = __mlx4_qp_lookup(dev, qpn); if (qp) - atomic_inc(&qp->refcount); + refcount_inc(&qp->refcount); spin_unlock(&qp_table->lock); @@ -66,7 +66,7 @@ void mlx4_qp_event(struct mlx4_dev *dev, u32 qpn, int event_type) qp->event(qp, event_type); - if (atomic_dec_and_test(&qp->refcount)) + if (refcount_dec_and_test(&qp->refcount)) complete(&qp->free); } @@ -420,7 +420,7 @@ int mlx4_qp_alloc(struct mlx4_dev *dev, int qpn, struct mlx4_qp *qp) if (err) goto err_icm; - atomic_set(&qp->refcount, 1); + refcount_set(&qp->refcount, 1); init_completion(&qp->free); return 0; @@ -520,7 +520,7 @@ EXPORT_SYMBOL_GPL(mlx4_qp_remove); void mlx4_qp_free(struct mlx4_dev *dev, struct mlx4_qp *qp) { - if (atomic_dec_and_test(&qp->refcount)) + if (refcount_dec_and_test(&qp->refcount)) complete(&qp->free); wait_for_completion(&qp->free); diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h index daac2e3..b8e19c4 100644 --- a/include/linux/mlx4/device.h +++ b/include/linux/mlx4/device.h @@ -768,7 +768,7 @@ struct mlx4_qp { int qpn; - atomic_t refcount; + refcount_t refcount; struct completion free; u8 usage; }; -- 2.7.4