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Subject: Re: [PATCH] vrf: Fix possible NULL pointer oops when delete nic
To:     "wangxiaogang (F)" <wangxiaogang3@huawei.com>, dsahern@kernel.org,
        shrijeet@gmail.com, davem@davemloft.net
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        hujunwei4@huawei.com, xuhanbing@huawei.com
References: <60e827cb-2bba-2b7e-55dc-651103e9905f@huawei.com>
From:   David Ahern <dsahern@gmail.com>
Message-ID: <7fe948a8-debd-e336-9584-e66153e90701@gmail.com>
Date:   Fri, 15 Nov 2019 09:59:47 -0700
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On 11/14/19 11:22 PM, wangxiaogang (F) wrote:
> diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
> index b8228f5..86c4b8c 100644
> --- a/drivers/net/vrf.c
> +++ b/drivers/net/vrf.c
> @@ -1427,6 +1427,9 @@ static int vrf_device_event(struct notifier_block *unused,
>  			goto out;
> 
>  		vrf_dev = netdev_master_upper_dev_get(dev);
> +		if (!vrf_dev)
> +			goto out;
> +
>  		vrf_del_slave(vrf_dev, dev);
>  	}
>  out:

BTW, I believe this is the wrong fix. A device can not be a VRF slave
AND not have an upper device. Something is fundamentally wrong.