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Commit 22d95b54 authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
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net_sched: add __rcu annotation to netdev->qdisc 



commit 5891cd5ec46c2c2eb6427cb54d214b149635dd0e upstream.

syzbot found a data-race [1] which lead me to add __rcu
annotations to netdev->qdisc, and proper accessors
to get LOCKDEP support.

[1]
BUG: KCSAN: data-race in dev_activate / qdisc_lookup_rcu

write to 0xffff888168ad6410 of 8 bytes by task 13559 on cpu 1:
 attach_default_qdiscs net/sched/sch_generic.c:1167 [inline]
 dev_activate+0x2ed/0x8f0 net/sched/sch_generic.c:1221
 __dev_open+0x2e9/0x3a0 net/core/dev.c:1416
 __dev_change_flags+0x167/0x3f0 net/core/dev.c:8139
 rtnl_configure_link+0xc2/0x150 net/core/rtnetlink.c:3150
 __rtnl_newlink net/core/rtnetlink.c:3489 [inline]
 rtnl_newlink+0xf4d/0x13e0 net/core/rtnetlink.c:3529
 rtnetlink_rcv_msg+0x745/0x7e0 net/core/rtnetlink.c:5594
 netlink_rcv_skb+0x14e/0x250 net/netlink/af_netlink.c:2494
 rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:5612
 netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
 netlink_unicast+0x602/0x6d0 net/netlink/af_netlink.c:1343
 netlink_sendmsg+0x728/0x850 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:705 [inline]
 sock_sendmsg net/socket.c:725 [inline]
 ____sys_sendmsg+0x39a/0x510 net/socket.c:2413
 ___sys_sendmsg net/socket.c:2467 [inline]
 __sys_sendmsg+0x195/0x230 net/socket.c:2496
 __do_sys_sendmsg net/socket.c:2505 [inline]
 __se_sys_sendmsg net/socket.c:2503 [inline]
 __x64_sys_sendmsg+0x42/0x50 net/socket.c:2503
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888168ad6410 of 8 bytes by task 13560 on cpu 0:
 qdisc_lookup_rcu+0x30/0x2e0 net/sched/sch_api.c:323
 __tcf_qdisc_find+0x74/0x3a0 net/sched/cls_api.c:1050
 tc_del_tfilter+0x1c7/0x1350 net/sched/cls_api.c:2211
 rtnetlink_rcv_msg+0x5ba/0x7e0 net/core/rtnetlink.c:5585
 netlink_rcv_skb+0x14e/0x250 net/netlink/af_netlink.c:2494
 rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:5612
 netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
 netlink_unicast+0x602/0x6d0 net/netlink/af_netlink.c:1343
 netlink_sendmsg+0x728/0x850 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:705 [inline]
 sock_sendmsg net/socket.c:725 [inline]
 ____sys_sendmsg+0x39a/0x510 net/socket.c:2413
 ___sys_sendmsg net/socket.c:2467 [inline]
 __sys_sendmsg+0x195/0x230 net/socket.c:2496
 __do_sys_sendmsg net/socket.c:2505 [inline]
 __se_sys_sendmsg net/socket.c:2503 [inline]
 __x64_sys_sendmsg+0x42/0x50 net/socket.c:2503
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffffffff85dee080 -> 0xffff88815d96ec00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 13560 Comm: syz-executor.2 Not tainted 5.17.0-rc3-syzkaller-00116-gf1baf68e1383-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Fixes: 470502de ("net: sched: unlock rules update API")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Vlad Buslov <vladbu@mellanox.com>
Reported-by: default avatarsyzbot <syzkaller@googlegroups.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarZubin Mithra <zsm@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 14b6ad56

include/linux/netdevice.h

+1 −1
Original line number Diff line number Diff line
@@ -1986,7 +1986,7 @@ struct net_device { 
	struct netdev_queue	*_tx ____cacheline_aligned_in_smp;

	unsigned int		num_tx_queues;

	unsigned int		real_num_tx_queues;

	struct Qdisc		*qdisc;

	struct Qdisc __rcu	*qdisc;

#ifdef CONFIG_NET_SCHED

	DECLARE_HASHTABLE	(qdisc_hash, 4);

#endif

net/core/rtnetlink.c

+4 −2
Original line number Diff line number Diff line
@@ -1593,6 +1593,7 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, 
{

	struct ifinfomsg *ifm;

	struct nlmsghdr *nlh;

	struct Qdisc *qdisc;



	ASSERT_RTNL();

	nlh = nlmsg_put(skb, pid, seq, type, sizeof(*ifm), flags);
@@ -1610,6 +1611,7 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, 
	if (tgt_netnsid >= 0 && nla_put_s32(skb, IFLA_TARGET_NETNSID, tgt_netnsid))

		goto nla_put_failure;



	qdisc = rtnl_dereference(dev->qdisc);

	if (nla_put_string(skb, IFLA_IFNAME, dev->name) ||

	    nla_put_u32(skb, IFLA_TXQLEN, dev->tx_queue_len) ||

	    nla_put_u8(skb, IFLA_OPERSTATE,
@@ -1628,8 +1630,8 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, 
#endif

	    put_master_ifindex(skb, dev) ||

	    nla_put_u8(skb, IFLA_CARRIER, netif_carrier_ok(dev)) ||

	    (dev->qdisc &&

	     nla_put_string(skb, IFLA_QDISC, dev->qdisc->ops->id)) ||

	    (qdisc &&

	     nla_put_string(skb, IFLA_QDISC, qdisc->ops->id)) ||

	    nla_put_ifalias(skb, dev) ||

	    nla_put_u32(skb, IFLA_CARRIER_CHANGES,

			atomic_read(&dev->carrier_up_count) +

net/sched/cls_api.c

+3 −3
Original line number Diff line number Diff line
@@ -1079,7 +1079,7 @@ static int __tcf_qdisc_find(struct net *net, struct Qdisc **q, 


	/* Find qdisc */

	if (!*parent) {

		*q = dev->qdisc;

		*q = rcu_dereference(dev->qdisc);

		*parent = (*q)->handle;

	} else {

		*q = qdisc_lookup_rcu(dev, TC_H_MAJ(*parent));
@@ -2552,7 +2552,7 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb) 


		parent = tcm->tcm_parent;

		if (!parent)

			q = dev->qdisc;

			q = rtnl_dereference(dev->qdisc);

		else

			q = qdisc_lookup(dev, TC_H_MAJ(tcm->tcm_parent));

		if (!q)
@@ -2938,7 +2938,7 @@ static int tc_dump_chain(struct sk_buff *skb, struct netlink_callback *cb) 


		parent = tcm->tcm_parent;

		if (!parent) {

			q = dev->qdisc;

			q = rtnl_dereference(dev->qdisc);

			parent = q->handle;

		} else {

			q = qdisc_lookup(dev, TC_H_MAJ(tcm->tcm_parent));

net/sched/sch_api.c

+12 −10
Original line number Diff line number Diff line
@@ -298,7 +298,7 @@ struct Qdisc *qdisc_lookup(struct net_device *dev, u32 handle) 


	if (!handle)

		return NULL;

	q = qdisc_match_from_root(dev->qdisc, handle);

	q = qdisc_match_from_root(rtnl_dereference(dev->qdisc), handle);

	if (q)

		goto out;
@@ -317,7 +317,7 @@ struct Qdisc *qdisc_lookup_rcu(struct net_device *dev, u32 handle) 


	if (!handle)

		return NULL;

	q = qdisc_match_from_root(dev->qdisc, handle);

	q = qdisc_match_from_root(rcu_dereference(dev->qdisc), handle);

	if (q)

		goto out;
@@ -1072,10 +1072,10 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent, 
skip:

		if (!ingress) {

			notify_and_destroy(net, skb, n, classid,

					   dev->qdisc, new);

					   rtnl_dereference(dev->qdisc), new);

			if (new && !new->ops->attach)

				qdisc_refcount_inc(new);

			dev->qdisc = new ? : &noop_qdisc;

			rcu_assign_pointer(dev->qdisc, new ? : &noop_qdisc);



			if (new && new->ops->attach)

				new->ops->attach(new);
@@ -1455,7 +1455,7 @@ static int tc_get_qdisc(struct sk_buff *skb, struct nlmsghdr *n, 
				q = dev_ingress_queue(dev)->qdisc_sleeping;

			}

		} else {

			q = dev->qdisc;

			q = rtnl_dereference(dev->qdisc);

		}

		if (!q) {

			NL_SET_ERR_MSG(extack, "Cannot find specified qdisc on specified device");
@@ -1544,7 +1544,7 @@ static int tc_modify_qdisc(struct sk_buff *skb, struct nlmsghdr *n, 
				q = dev_ingress_queue(dev)->qdisc_sleeping;

			}

		} else {

			q = dev->qdisc;

			q = rtnl_dereference(dev->qdisc);

		}



		/* It may be default qdisc, ignore it */
@@ -1766,7 +1766,8 @@ static int tc_dump_qdisc(struct sk_buff *skb, struct netlink_callback *cb) 
			s_q_idx = 0;

		q_idx = 0;



		if (tc_dump_qdisc_root(dev->qdisc, skb, cb, &q_idx, s_q_idx,

		if (tc_dump_qdisc_root(rtnl_dereference(dev->qdisc),

				       skb, cb, &q_idx, s_q_idx,

				       true, tca[TCA_DUMP_INVISIBLE]) < 0)

			goto done;
@@ -2042,7 +2043,7 @@ static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n, 
		} else if (qid1) {

			qid = qid1;

		} else if (qid == 0)

			qid = dev->qdisc->handle;

			qid = rtnl_dereference(dev->qdisc)->handle;



		/* Now qid is genuine qdisc handle consistent

		 * both with parent and child.
@@ -2053,7 +2054,7 @@ static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n, 
			portid = TC_H_MAKE(qid, portid);

	} else {

		if (qid == 0)

			qid = dev->qdisc->handle;

			qid = rtnl_dereference(dev->qdisc)->handle;

	}



	/* OK. Locate qdisc */
@@ -2214,7 +2215,8 @@ static int tc_dump_tclass(struct sk_buff *skb, struct netlink_callback *cb) 
	s_t = cb->args[0];

	t = 0;



	if (tc_dump_tclass_root(dev->qdisc, skb, tcm, cb, &t, s_t, true) < 0)

	if (tc_dump_tclass_root(rtnl_dereference(dev->qdisc),

				skb, tcm, cb, &t, s_t, true) < 0)

		goto done;



	dev_queue = dev_ingress_queue(dev);

net/sched/sch_generic.c

+12 −10
Original line number Diff line number Diff line
@@ -1106,18 +1106,20 @@ static void attach_default_qdiscs(struct net_device *dev) 
	if (!netif_is_multiqueue(dev) ||

	    dev->priv_flags & IFF_NO_QUEUE) {

		netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);

		dev->qdisc = txq->qdisc_sleeping;

		qdisc_refcount_inc(dev->qdisc);

		qdisc = txq->qdisc_sleeping;

		rcu_assign_pointer(dev->qdisc, qdisc);

		qdisc_refcount_inc(qdisc);

	} else {

		qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);

		if (qdisc) {

			dev->qdisc = qdisc;

			rcu_assign_pointer(dev->qdisc, qdisc);

			qdisc->ops->attach(qdisc);

		}

	}



#ifdef CONFIG_NET_SCHED

	if (dev->qdisc != &noop_qdisc)

		qdisc_hash_add(dev->qdisc, false);

	if (qdisc != &noop_qdisc)

		qdisc_hash_add(qdisc, false);

#endif

}
@@ -1147,7 +1149,7 @@ void dev_activate(struct net_device *dev) 
	 * and noqueue_qdisc for virtual interfaces

	 */



	if (dev->qdisc == &noop_qdisc)

	if (rtnl_dereference(dev->qdisc) == &noop_qdisc)

		attach_default_qdiscs(dev);



	if (!netif_carrier_ok(dev))
@@ -1316,7 +1318,7 @@ static int qdisc_change_tx_queue_len(struct net_device *dev, 
void dev_qdisc_change_real_num_tx(struct net_device *dev,

				  unsigned int new_real_tx)

{

	struct Qdisc *qdisc = dev->qdisc;

	struct Qdisc *qdisc = rtnl_dereference(dev->qdisc);



	if (qdisc->ops->change_real_num_tx)

		qdisc->ops->change_real_num_tx(qdisc, new_real_tx);
@@ -1356,7 +1358,7 @@ static void dev_init_scheduler_queue(struct net_device *dev, 


void dev_init_scheduler(struct net_device *dev)

{

	dev->qdisc = &noop_qdisc;

	rcu_assign_pointer(dev->qdisc, &noop_qdisc);

	netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);

	if (dev_ingress_queue(dev))

		dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
@@ -1384,8 +1386,8 @@ void dev_shutdown(struct net_device *dev) 
	netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);

	if (dev_ingress_queue(dev))

		shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);

	qdisc_put(dev->qdisc);

	dev->qdisc = &noop_qdisc;

	qdisc_put(rtnl_dereference(dev->qdisc));

	rcu_assign_pointer(dev->qdisc, &noop_qdisc);



	WARN_ON(timer_pending(&dev->watchdog_timer));

}