linux-kernel - Re: [BUG] net: macb: Use-After-Free when removing the module

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Message-ID: <6a92bf85-4680-b0cf-aaa8-eb52d0a0adde@microchip.com>
Date:   Fri, 4 Mar 2022 10:49:40 +0100
From:   Nicolas Ferre <nicolas.ferre@...rochip.com>
To:     Jakub Kicinski <kuba@...nel.org>, Zheyu Ma <zheyuma97@...il.com>
CC:     <claudiu.beznea@...rochip.com>, <netdev@...r.kernel.org>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] net: macb: Use-After-Free when removing the module

On 03/03/2022 at 16:57, Jakub Kicinski wrote:
> On Thu, 3 Mar 2022 20:24:53 +0800 Zheyu Ma wrote:
>> When removing the macb_pci module, the driver will cause a UAF bug.
>>
>> Commit d82d5303c4c5 ("net: macb: fix use after free on rmmod") moves
>> the platform_device_unregister() after clk_unregister(), but this
>> introduces another UAF bug.
> 
> The layering is all weird here. macb_probe() should allocate a private
> structure for the _PCI driver_ which it can then attach to
> struct pci_dev *pdev as driver data. Then free it in remove.
> It shouldn't stuff its information into the platform device.

The PCI file was added as an optional layer to the original "platform" 
macb driver. I think it was added to run some experiments in some test 
conditions at Cadence.

> Are you willing to send a fix like that?

I would prefer that we don't change too much the driver in the normal 
working conditions: meaning without the PCI additional glue.

my $0.02.

Regards,
   Nicolas

-- 
Nicolas Ferre