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net, sched: convert Qdisc.refcnt from atomic_t to refcount_t

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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>
This commit is contained in:
Reshetova, Elena 2017-07-04 15:53:07 +03:00 committed by David S. Miller
parent edcd9270be
commit 7b93640502
3 changed files with 10 additions and 9 deletions
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3
include/net/sch_generic.h
View File

@ -9,6 +9,7 @@
#include <linux/percpu.h>
#include <linux/dynamic_queue_limits.h>
#include <linux/list.h>
#include <linux/refcount.h>
#include <net/gen_stats.h>
#include <net/rtnetlink.h>
@ -95,7 +96,7 @@ struct Qdisc {
struct sk_buff *skb_bad_txq;
struct rcu_head rcu_head;
int padded;
atomic_t refcnt;
refcount_t refcnt;
spinlock_t busylock ____cacheline_aligned_in_smp;
};

8
net/sched/sch_api.c
View File

@ -839,7 +839,7 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
old = dev_graft_qdisc(dev_queue, new);
if (new && i > 0)
atomic_inc(&new->refcnt);
refcount_inc(&new->refcnt);
if (!ingress)
qdisc_destroy(old);
@ -850,7 +850,7 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
notify_and_destroy(net, skb, n, classid,
dev->qdisc, new);
if (new && !new->ops->attach)
atomic_inc(&new->refcnt);
refcount_inc(&new->refcnt);
dev->qdisc = new ? : &noop_qdisc;
if (new && new->ops->attach)
@ -1259,7 +1259,7 @@ static int tc_modify_qdisc(struct sk_buff *skb, struct nlmsghdr *n,
if (q == p ||
(p && check_loop(q, p, 0)))
return -ELOOP;
atomic_inc(&q->refcnt);
refcount_inc(&q->refcnt);
goto graft;
} else {
if (!q)
@ -1374,7 +1374,7 @@ static int tc_fill_qdisc(struct sk_buff *skb, struct Qdisc *q, u32 clid,
tcm->tcm_ifindex = qdisc_dev(q)->ifindex;
tcm->tcm_parent = clid;
tcm->tcm_handle = q->handle;
tcm->tcm_info = atomic_read(&q->refcnt);
tcm->tcm_info = refcount_read(&q->refcnt);
if (nla_put_string(skb, TCA_KIND, q->ops->id))
goto nla_put_failure;
if (q->ops->dump && q->ops->dump(q, skb) < 0)

8
net/sched/sch_generic.c
View File

@ -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) {