[PATCH 04/15] drivers, net, mlx4: convert mlx4_qp.refcount from atomic_t to refcount_t

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


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 <keescook@xxxxxxxxxxxx>
Reviewed-by: David Windsor <dwindsor@xxxxxxxxx>
Reviewed-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
Signed-off-by: Elena Reshetova <elena.reshetova@xxxxxxxxx>
 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);
@@ -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))
@@ -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);
 	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))
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;

To unsubscribe from this list: send the line "unsubscribe linux-ppp" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Index of Archives]     [Linux Audio Users]     [Linux for Hams]     [Kernel Newbies]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Video 4 Linux]     [Fedora Users]

  Powered by Linux