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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>
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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/net/sch_generic.h
View File

@ -9,6 +9,7 @@
#include <linux/percpu.h> #include <linux/percpu.h>
#include <linux/dynamic_queue_limits.h> #include <linux/dynamic_queue_limits.h>
#include <linux/list.h> #include <linux/list.h>
#include <linux/refcount.h>
#include <net/gen_stats.h> #include <net/gen_stats.h>
#include <net/rtnetlink.h> #include <net/rtnetlink.h>
@ -95,7 +96,7 @@ struct Qdisc {
struct sk_buff *skb_bad_txq; struct sk_buff *skb_bad_txq;
struct rcu_head rcu_head; struct rcu_head rcu_head;
int padded; int padded;
atomic_t refcnt; refcount_t refcnt;
spinlock_t busylock ____cacheline_aligned_in_smp; 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); old = dev_graft_qdisc(dev_queue, new);
if (new && i > 0) if (new && i > 0)
atomic_inc(&new->refcnt); refcount_inc(&new->refcnt);
if (!ingress) if (!ingress)
qdisc_destroy(old); qdisc_destroy(old);
@ -850,7 +850,7 @@ skip:
notify_and_destroy(net, skb, n, classid, notify_and_destroy(net, skb, n, classid,
dev->qdisc, new); dev->qdisc, new);
if (new && !new->ops->attach) if (new && !new->ops->attach)
atomic_inc(&new->refcnt); refcount_inc(&new->refcnt);
dev->qdisc = new ? : &noop_qdisc; dev->qdisc = new ? : &noop_qdisc;
if (new && new->ops->attach) if (new && new->ops->attach)
@ -1259,7 +1259,7 @@ replay:
if (q == p || if (q == p ||
(p && check_loop(q, p, 0))) (p && check_loop(q, p, 0)))
return -ELOOP; return -ELOOP;
atomic_inc(&q->refcnt); refcount_inc(&q->refcnt);
goto graft; goto graft;
} else { } else {
if (!q) 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_ifindex = qdisc_dev(q)->ifindex;
tcm->tcm_parent = clid; tcm->tcm_parent = clid;
tcm->tcm_handle = q->handle; 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)) if (nla_put_string(skb, TCA_KIND, q->ops->id))
goto nla_put_failure; goto nla_put_failure;
if (q->ops->dump && q->ops->dump(q, skb) < 0) 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->dequeue = ops->dequeue;
sch->dev_queue = dev_queue; sch->dev_queue = dev_queue;
dev_hold(dev); dev_hold(dev);
atomic_set(&sch->refcnt, 1); refcount_set(&sch->refcnt, 1);
return sch; return sch;
errout: errout:
@ -701,7 +701,7 @@ void qdisc_destroy(struct Qdisc *qdisc)
const struct Qdisc_ops *ops = qdisc->ops; const struct Qdisc_ops *ops = qdisc->ops;
if (qdisc->flags & TCQ_F_BUILTIN || if (qdisc->flags & TCQ_F_BUILTIN ||
!atomic_dec_and_test(&qdisc->refcnt)) !refcount_dec_and_test(&qdisc->refcnt))
return; return;
#ifdef CONFIG_NET_SCHED #ifdef CONFIG_NET_SCHED
@ -739,7 +739,7 @@ struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
spin_lock_bh(root_lock); spin_lock_bh(root_lock);
/* Prune old scheduler */ /* Prune old scheduler */
if (oqdisc && atomic_read(&oqdisc->refcnt) <= 1) if (oqdisc && refcount_read(&oqdisc->refcnt) <= 1)
qdisc_reset(oqdisc); qdisc_reset(oqdisc);
/* ... and graft new one */ /* ... and graft new one */
@ -785,7 +785,7 @@ static void attach_default_qdiscs(struct net_device *dev)
dev->priv_flags & IFF_NO_QUEUE) { dev->priv_flags & IFF_NO_QUEUE) {
netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL); netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
dev->qdisc = txq->qdisc_sleeping; dev->qdisc = txq->qdisc_sleeping;
atomic_inc(&dev->qdisc->refcnt); refcount_inc(&dev->qdisc->refcnt);
} else { } else {
qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT); qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT);
if (qdisc) { if (qdisc) {