linux-kernel - [PATCH 3.16.y-ckt 104/110] net_sched: invoke ->attach() after setting dev->qdisc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1433512713-22984-105-git-send-email-luis.henriques@canonical.com>
Date:	Fri,  5 Jun 2015 14:58:27 +0100
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Jamal Hadi Salim <jhs@...atatu.com>,
	Cong Wang <xiyou.wangcong@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 104/110] net_sched: invoke ->attach() after setting dev->qdisc

3.16.7-ckt13 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: WANG Cong <xiyou.wangcong@...il.com>

commit 86e363dc3b50bfd50a1f315934583fbda673ab8d upstream.

For mq qdisc, we add per tx queue qdisc to root qdisc
for display purpose, however, that happens too early,
before the new dev->qdisc is finally set, this causes
q->list points to an old root qdisc which is going to be
freed right before assigning with a new one.

Fix this by moving ->attach() after setting dev->qdisc.

For the record, this fixes the following crash:

 ------------[ cut here ]------------
 WARNING: CPU: 1 PID: 975 at lib/list_debug.c:59 __list_del_entry+0x5a/0x98()
 list_del corruption. prev->next should be ffff8800d1998ae8, but was 6b6b6b6b6b6b6b6b
 CPU: 1 PID: 975 Comm: tc Not tainted 4.1.0-rc4+ #1019
 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  0000000000000009 ffff8800d73fb928 ffffffff81a44e7f 0000000047574756
  ffff8800d73fb978 ffff8800d73fb968 ffffffff810790da ffff8800cfc4cd20
  ffffffff814e725b ffff8800d1998ae8 ffffffff82381250 0000000000000000
 Call Trace:
  [<ffffffff81a44e7f>] dump_stack+0x4c/0x65
  [<ffffffff810790da>] warn_slowpath_common+0x9c/0xb6
  [<ffffffff814e725b>] ? __list_del_entry+0x5a/0x98
  [<ffffffff81079162>] warn_slowpath_fmt+0x46/0x48
  [<ffffffff81820eb0>] ? dev_graft_qdisc+0x5e/0x6a
  [<ffffffff814e725b>] __list_del_entry+0x5a/0x98
  [<ffffffff814e72a7>] list_del+0xe/0x2d
  [<ffffffff81822f05>] qdisc_list_del+0x1e/0x20
  [<ffffffff81820cd1>] qdisc_destroy+0x30/0xd6
  [<ffffffff81822676>] qdisc_graft+0x11d/0x243
  [<ffffffff818233c1>] tc_get_qdisc+0x1a6/0x1d4
  [<ffffffff810b5eaf>] ? mark_lock+0x2e/0x226
  [<ffffffff817ff8f5>] rtnetlink_rcv_msg+0x181/0x194
  [<ffffffff817ff72e>] ? rtnl_lock+0x17/0x19
  [<ffffffff817ff72e>] ? rtnl_lock+0x17/0x19
  [<ffffffff817ff774>] ? __rtnl_unlock+0x17/0x17
  [<ffffffff81855dc6>] netlink_rcv_skb+0x4d/0x93
  [<ffffffff817ff756>] rtnetlink_rcv+0x26/0x2d
  [<ffffffff818544b2>] netlink_unicast+0xcb/0x150
  [<ffffffff81161db9>] ? might_fault+0x59/0xa9
  [<ffffffff81854f78>] netlink_sendmsg+0x4fa/0x51c
  [<ffffffff817d6e09>] sock_sendmsg_nosec+0x12/0x1d
  [<ffffffff817d8967>] sock_sendmsg+0x29/0x2e
  [<ffffffff817d8cf3>] ___sys_sendmsg+0x1b4/0x23a
  [<ffffffff8100a1b8>] ? native_sched_clock+0x35/0x37
  [<ffffffff810a1d83>] ? sched_clock_local+0x12/0x72
  [<ffffffff810a1fd4>] ? sched_clock_cpu+0x9e/0xb7
  [<ffffffff810def2a>] ? current_kernel_time+0xe/0x32
  [<ffffffff810b4bc5>] ? lock_release_holdtime.part.29+0x71/0x7f
  [<ffffffff810ddebf>] ? read_seqcount_begin.constprop.27+0x5f/0x76
  [<ffffffff810b6292>] ? trace_hardirqs_on_caller+0x17d/0x199
  [<ffffffff811b14d5>] ? __fget_light+0x50/0x78
  [<ffffffff817d9808>] __sys_sendmsg+0x42/0x60
  [<ffffffff817d9838>] SyS_sendmsg+0x12/0x1c
  [<ffffffff81a50e97>] system_call_fastpath+0x12/0x6f
 ---[ end trace ef29d3fb28e97ae7 ]---

For long term, we probably need to clean up the qdisc_graft() code
in case it hides other bugs like this.

Fixes: 95dc19299f74 ("pkt_sched: give visibility to mq slave qdiscs")
Cc: Jamal Hadi Salim <jhs@...atatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
Acked-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 net/sched/sch_api.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 58bed7599db7..04de05ae7c5e 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -812,10 +812,8 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
 		if (dev->flags & IFF_UP)
 			dev_deactivate(dev);
 
-		if (new && new->ops->attach) {
-			new->ops->attach(new);
-			num_q = 0;
-		}
+		if (new && new->ops->attach)
+			goto skip;
 
 		for (i = 0; i < num_q; i++) {
 			struct netdev_queue *dev_queue = dev_ingress_queue(dev);
@@ -831,12 +829,16 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
 				qdisc_destroy(old);
 		}
 
+skip:
 		if (!ingress) {
 			notify_and_destroy(net, skb, n, classid,
 					   dev->qdisc, new);
 			if (new && !new->ops->attach)
 				atomic_inc(&new->refcnt);
 			dev->qdisc = new ? : &noop_qdisc;
+
+			if (new && new->ops->attach)
+				new->ops->attach(new);
 		} else {
 			notify_and_destroy(net, skb, n, classid, old, new);
 		}
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/