netdev - Re: [Patch net] net_sched: fix error path in red

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Message-ID: <87lfhzdo3l.fsf@nvidia.com>
Date:   Fri, 28 Aug 2020 13:08:46 +0200
From:   Petr Machata <petrm@...dia.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
CC:     <netdev@...r.kernel.org>,
        <syzbot+b33c1cb0a30ebdc8a5f9@...kaller.appspotmail.com>,
        <syzbot+e5ea5f8a3ecfd4427a1c@...kaller.appspotmail.com>,
        Petr Machata <petrm@...lanox.com>
Subject: Re: [Patch net] net_sched: fix error path in red_init()


Cong Wang <xiyou.wangcong@...il.com> writes:

> When ->init() fails, ->destroy() is called to clean up.
> So it is unnecessary to clean up in red_init(), and it
> would cause some refcount underflow.

Hmm, yeah, qdisc_put() would get called twice. A surprising API, the
init needs to make sure to always bring the qdisc into destroyable
state. But qevents are like that after kzalloc, so the fix looks
correct.

Reviewed-by: Petr Machata <petrm@...dia.com>

Thanks!