netdev - Re: [PATCH net 0/2] NULL pointer dereference in {ipvlan|macvlan}_port

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Date:   Fri, 3 Nov 2017 09:39:45 -0700
From:   Girish Moodalbail <girish.moodalbail@...cle.com>
To:     David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net 0/2] NULL pointer dereference in
 {ipvlan|macvlan}_port_destroy

On 11/2/17 10:05 PM, David Miller wrote:
> From: Girish Moodalbail <girish.moodalbail@...cle.com>
> Date: Tue, 31 Oct 2017 09:39:45 -0700
> 
>> When call to register_netdevice() (called from ipvlan_link_new())
>> fails, inside that function we call ipvlan_uninit() (through
>> ndo_uninit()) to destroy the ipvlan port. Upon returning
>> unsuccessfully from register_netdevice() we go ahead and call
>> ipvlan_port_destroy() again which causes NULL pointer dereference
>> panic.
> 
> The problem is that ipvlan doesn't follow the proper convention that
> ->ndo_uninit() must only release resources allocated by ->ndo_init().
> 
> What needs to happen is that the port allocation occur in
> ->ndo_init().

I agree, will send out V2. I initially started off making them (ndo_init and 
ndo_uninit) symmetric by moving the port destruction out of ndo_uninit(), but I 
hit some WARN() errors. Will figure it out.

thanks,
~Girish

> 
> Your fix, while solving some cases, does not fully cover all of the
> posibiities due to this bug.
> 
> Please fix this correctly by moving the port allocation and related
> setup from link creation to ->ndo_init().
> 
> Thank you.
>