net, sched: convert Qdisc.refcnt from atomic_t to refcount_t
refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 52a2c55..57ba406 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -633,7 +633,7 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
sch->dequeue = ops->dequeue;
sch->dev_queue = dev_queue;
dev_hold(dev);
- atomic_set(&sch->refcnt, 1);
+ refcount_set(&sch->refcnt, 1);
return sch;
errout:
@@ -701,7 +701,7 @@ void qdisc_destroy(struct Qdisc *qdisc)
const struct Qdisc_ops *ops = qdisc->ops;
if (qdisc->flags & TCQ_F_BUILTIN ||
- !atomic_dec_and_test(&qdisc->refcnt))
+ !refcount_dec_and_test(&qdisc->refcnt))
return;
#ifdef CONFIG_NET_SCHED
@@ -739,7 +739,7 @@ struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
spin_lock_bh(root_lock);
/* Prune old scheduler */
- if (oqdisc && atomic_read(&oqdisc->refcnt) <= 1)
+ if (oqdisc && refcount_read(&oqdisc->refcnt) <= 1)
qdisc_reset(oqdisc);
/* ... and graft new one */
@@ -785,7 +785,7 @@ static void attach_default_qdiscs(struct net_device *dev)
dev->priv_flags & IFF_NO_QUEUE) {
netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
dev->qdisc = txq->qdisc_sleeping;
- atomic_inc(&dev->qdisc->refcnt);
+ refcount_inc(&dev->qdisc->refcnt);
} else {
qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT);
if (qdisc) {