netdev - Re: [PATCH net] net: fix memory leak in register

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Message-ID: <00b0ef28-ebb4-c036-0082-093549251b16@huawei.com>
Date:   Mon, 30 Nov 2020 19:13:18 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     Toshiaki Makita <toshiaki.makita1@...il.com>
CC:     <davem@...emloft.net>, <kuba@...nel.org>, <rkovhaev@...il.com>,
        Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net] net: fix memory leak in register_netdevice() on error
 path


On 2020/11/29 21:56, Toshiaki Makita wrote:
> On 2020/11/26 22:23, Yang Yingliang wrote:
> ...
>> Reported-by: Hulk Robot <hulkci@...wei.com>
>> Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
>> ---
>>   net/core/dev.c | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/net/core/dev.c b/net/core/dev.c
>> index 82dc6b48e45f..907204395b64 100644
>> --- a/net/core/dev.c
>> +++ b/net/core/dev.c
>> @@ -10000,6 +10000,17 @@ int register_netdevice(struct net_device *dev)
>>       ret = notifier_to_errno(ret);
>>       if (ret) {
>>           rollback_registered(dev);
>> +        /*
>> +         * In common case, priv_destructor() will be
>
> As per netdev-faq, the comment style should be
>
> /* foobar blah blah blah
>  * another line of text
>  */
>
> rather than
>
> /*
>  * foobar blah blah blah
>  * another line of text
>  */
>
>> +         * called in netdev_run_todo() after calling
>> +         * ndo_uninit() in rollback_registered().
>> +         * But in this case, priv_destructor() will
>> +         * never be called, then it causes memory
>> +         * leak, so we should call priv_destructor()
>> +         * here.
>> +         */
>> +        if (dev->priv_destructor)
>> +            dev->priv_destructor(dev);
>
> To be in line with netdev_run_todo(), I think priv_destructor() should be
> called after "dev->reg_state = NETREG_UNREGISTERED".
OK,  I will send a v2 later.
>
> Toshiaki Makita
>
>>           rcu_barrier();
>>             dev->reg_state = NETREG_UNREGISTERED;
>>