netdev - Re: [PATCH v3] tun: fix use-after-free when register netdev failed

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Date:   Tue, 10 Sep 2019 10:36:30 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Yang Yingliang <yangyingliang@...wei.com>
Cc:     David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
        eric dumazet <eric.dumazet@...il.com>,
        xiyou wangcong <xiyou.wangcong@...il.com>,
        weiyongjun1@...wei.com
Subject: Re: [PATCH v3] tun: fix use-after-free when register netdev failed


On 2019/9/10 上午10:31, Yang Yingliang wrote:
>>>
>>>               if (!(tun->flags & IFF_PERSIST) &&
>>> -                tun->dev->reg_state == NETREG_REGISTERED)
>>> +                tun->dev->reg_state == NETREG_REGISTERED) {
>>> +                tun->flags &= ~TUN_DEV_REGISTERED;
>>
>> As I said for previous versions. It's not good that try to invent new
>> internal state like this, and you need carefully to deal with the
>> synchronization, it could be lock or barriers. Consider the
>> synchronization of tun is already complex, let's better try to avoid
>> adding more but using exist mechanism, e.g pointer publishing through 
>> RCU.
> OK, need I post a V4 by using the diff file you sent ? 


Yes, please.

Thanks