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Date:   Tue, 22 Mar 2022 07:03:59 -0700
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Subject: Re: [PATCH net-next v3 1/3] net: ipvlan: fix potential UAF problem
 for phy_dev
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To:     Ziyang Xuan <william.xuanziyang@huawei.com>, davem@davemloft.net,
        kuba@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org
Cc:     edumazet@google.com, brianvv@google.com,
        linux-kernel@vger.kernel.org
References: <cover.1647664114.git.william.xuanziyang@huawei.com>
 <abef9f7ad2c6e6b8ae053225766d34f3fc930ddf.1647664114.git.william.xuanziyang@huawei.com>
From:   Eric Dumazet <eric.dumazet@gmail.com>
In-Reply-To: <abef9f7ad2c6e6b8ae053225766d34f3fc930ddf.1647664114.git.william.xuanziyang@huawei.com>
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On 3/19/22 02:52, Ziyang Xuan wrote:
> There is a known scenario can trigger UAF problem for lower
> netdevice as following:


But this known scenario never happens.

So maybe you should not add it 'in the future'


>
> Someone module puts the NETDEV_UNREGISTER event handler to a
> work, and lower netdevice is accessed in the work handler. But
> when the work is excuted, lower netdevice has been destroyed
> because upper netdevice did not get reference to lower netdevice
> correctly.

Again, whoever would like to use a work queue would also

need to hold a reference on the device.

Regardless of ipvlan being used or not.


>
> Although it can not happen for ipvlan now because there is no
> way to access phy_dev outside ipvlan. But it is necessary to
> add the reference operation to phy_dev to avoid the potential
> UAF problem in the future.
>
> Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
> ---


Your patch makes no sense to me really.