Commit 0068895f authored by Elena Reshetova's avatar Elena Reshetova Committed by David S. Miller

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: 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 ff61b5e3
...@@ -55,7 +55,7 @@ void mlx4_qp_event(struct mlx4_dev *dev, u32 qpn, int event_type) ...@@ -55,7 +55,7 @@ void mlx4_qp_event(struct mlx4_dev *dev, u32 qpn, int event_type)
qp = __mlx4_qp_lookup(dev, qpn); qp = __mlx4_qp_lookup(dev, qpn);
if (qp) if (qp)
atomic_inc(&qp->refcount); refcount_inc(&qp->refcount);
spin_unlock(&qp_table->lock); spin_unlock(&qp_table->lock);
...@@ -66,7 +66,7 @@ void mlx4_qp_event(struct mlx4_dev *dev, u32 qpn, int event_type) ...@@ -66,7 +66,7 @@ void mlx4_qp_event(struct mlx4_dev *dev, u32 qpn, int event_type)
qp->event(qp, event_type); qp->event(qp, event_type);
if (atomic_dec_and_test(&qp->refcount)) if (refcount_dec_and_test(&qp->refcount))
complete(&qp->free); complete(&qp->free);
} }
...@@ -420,7 +420,7 @@ int mlx4_qp_alloc(struct mlx4_dev *dev, int qpn, struct mlx4_qp *qp) ...@@ -420,7 +420,7 @@ int mlx4_qp_alloc(struct mlx4_dev *dev, int qpn, struct mlx4_qp *qp)
if (err) if (err)
goto err_icm; goto err_icm;
atomic_set(&qp->refcount, 1); refcount_set(&qp->refcount, 1);
init_completion(&qp->free); init_completion(&qp->free);
return 0; return 0;
...@@ -520,7 +520,7 @@ EXPORT_SYMBOL_GPL(mlx4_qp_remove); ...@@ -520,7 +520,7 @@ EXPORT_SYMBOL_GPL(mlx4_qp_remove);
void mlx4_qp_free(struct mlx4_dev *dev, struct mlx4_qp *qp) 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); complete(&qp->free);
wait_for_completion(&qp->free); wait_for_completion(&qp->free);
......
...@@ -768,7 +768,7 @@ struct mlx4_qp { ...@@ -768,7 +768,7 @@ struct mlx4_qp {
int qpn; int qpn;
atomic_t refcount; refcount_t refcount;
struct completion free; struct completion free;
u8 usage; u8 usage;
}; };
......
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