[PATCH 05/15] drivers, net, mlx4: convert mlx4_srq.refcount from atomic_t to refcount_t
From: elena.reshetova@intel.com (Elena Reshetova)
Date: 2017-10-20 07:24:31
Also in:
linux-hams, linux-mediatek, linux-rdma, lkml, netdev
Subsystem:
mellanox mlx4 ib driver, mellanox mlx4 core vpi driver, networking drivers, the rest · Maintainers:
Yishai Hadas, Tariq Toukan, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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: Kees Cook <redacted> Reviewed-by: David Windsor <redacted> Reviewed-by: Hans Liljestrand <redacted> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> --- drivers/net/ethernet/mellanox/mlx4/srq.c | 8 ++++---- include/linux/mlx4/device.h | 2 +- 2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx4/srq.c b/drivers/net/ethernet/mellanox/mlx4/srq.c
index bedf521..cbe4d97 100644
--- a/drivers/net/ethernet/mellanox/mlx4/srq.c
+++ b/drivers/net/ethernet/mellanox/mlx4/srq.c@@ -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);
diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h
index b8e19c4..a9b5fed 100644
--- a/include/linux/mlx4/device.h
+++ b/include/linux/mlx4/device.h@@ -781,7 +781,7 @@ struct mlx4_srq { int max_gs; int wqe_shift; - atomic_t refcount; + refcount_t refcount; struct completion free; };
--
2.7.4