From a4b51a9f83c6d359ff8fc0c66009283b6fdeeaf8 Mon Sep 17 00:00:00 2001 From: Elena Reshetova Date: Fri, 20 Oct 2017 10:23:40 +0300 Subject: [PATCH] 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 Reviewed-by: David Windsor Reviewed-by: Hans Liljestrand Signed-off-by: Elena Reshetova Signed-off-by: David S. Miller --- 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 336d4738b807..1016e05c7ec7 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 95898847c7d4..6a57ec2f1ef7 100644 --- a/include/linux/mlx5/cq.h +++ b/include/linux/mlx5/cq.h @@ -35,7 +35,7 @@ #include #include - +#include 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;