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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Cong Wang <cwang@twopensource.com>
Cc: pageexec@freemail.hu, Daniele Fucini <dfucini@gmail.com>,
	netdev <netdev@vger.kernel.org>,
	Jamal Hadi Salim <jhs@mojatatu.com>,
	David Miller <davem@davemloft.net>,
	spender@grsecurity.net, re.emese@gmail.com
Subject: Re: size overflow in function qdisc_tree_decrease_qlen net/sched/sch_api.c
Date: Tue, 01 Dec 2015 11:09:24 -0800	[thread overview]
Message-ID: <1448996964.16994.2.camel@edumazet-glaptop2.roam.corp.google.com> (raw)
In-Reply-To: <CAHA+R7NiYjhE5dY7HPkWuoTA5WMqF3zPyCFk5i3LYTUrYD7gYA@mail.gmail.com>

On Tue, 2015-12-01 at 10:43 -0800, Cong Wang wrote:

> This smells hacky... Another way to fix this is to hold the qdisc tree
> lock in mq_dump(), since it is not a hot path (comparing with
> enqueue/dequeue)?

Really ? Which qdisc tree lock will protect you exactly ???

Whole point of MQ is that each TX queue has its own lock.

So multiple cpus can call qdisc_tree_decrease_qlen() at the same time,
holding their own lock.

Clearly modifying mq 'data' is wrong.

  reply	other threads:[~2015-12-01 19:09 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-01  1:00 size overflow in function qdisc_tree_decrease_qlen net/sched/sch_api.c Daniele Fucini
2015-12-01  4:50 ` Cong Wang
2015-12-01 11:19   ` Daniele Fucini
2015-12-01 14:06     ` Eric Dumazet
2015-12-01 14:10       ` Eric Dumazet
2015-12-01 16:13         ` PaX Team
2015-12-01 16:34           ` Eric Dumazet
2015-12-01 18:43             ` Cong Wang
2015-12-01 19:09               ` Eric Dumazet [this message]
2015-12-01 19:17                 ` Cong Wang
2015-12-01 20:06                   ` Eric Dumazet
2015-12-01 22:33                     ` Eric Dumazet
2015-12-01 22:47                       ` Cong Wang
2015-12-01 23:10                         ` Eric Dumazet
2015-12-02  4:08                           ` [PATCH net] net_sched: fix qdisc_tree_decrease_qlen() races Eric Dumazet
2015-12-03 19:59                             ` David Miller
2015-12-01 22:40                     ` size overflow in function qdisc_tree_decrease_qlen net/sched/sch_api.c Cong Wang
2015-12-01 14:15       ` Eric Dumazet
2015-12-01 19:13         ` Daniele Fucini

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