linux-kernel - Re: [Intel-wired-lan] [RFT net-next PATCH RESEND 0/2] ethernet: intel: fix freeing uninitialized pointers with _

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Message-ID: <df193ddb-4591-417d-8d62-42d99d6d468f@intel.com>
Date: Wed, 3 Dec 2025 09:45:19 +0100
From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
To: ally heev <allyheev@...il.com>, Tony Nguyen <anthony.l.nguyen@...el.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
CC: <intel-wired-lan@...ts.osuosl.org>, <netdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Dan Carpenter <dan.carpenter@...aro.org>,
	Andrew Lunn <andrew+netdev@...n.ch>, "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>, Alexander Lobakin
	<aleksander.lobakin@...el.com>, Simon Horman <horms@...nel.org>
Subject: Re: [Intel-wired-lan] [RFT net-next PATCH RESEND 0/2] ethernet:
 intel: fix freeing uninitialized pointers with __free

On 12/3/25 09:09, ally heev wrote:
> On Tue, 2025-12-02 at 10:17 -0800, Tony Nguyen wrote:
>>
>> On 12/2/2025 11:47 AM, ally heev wrote:
>>> On Mon, 2025-12-01 at 13:40 -0800, Tony Nguyen wrote:
>>>>
>>>> On 11/23/2025 11:40 PM, Ally Heev wrote:
>>>>> Uninitialized pointers with `__free` attribute can cause undefined
>>>>> behavior as the memory assigned randomly to the pointer is freed
>>>>> automatically when the pointer goes out of scope.
>>>>>
>>>>> We could just fix it by initializing the pointer to NULL, but, as usage of
>>>>> cleanup attributes is discouraged in net [1], trying to achieve cleanup
>>>>> using goto
>>>>
>>>> These two drivers already have multiple other usages of this. All the
>>>> other instances initialize to NULL; I'd prefer to see this do the same
>>>> over changing this single instance.
>>>>
>>>
>>> Other usages are slightly complicated to be refactored and might need
>>> good testing. Do you want me to do it in a different series?
>>
>> Hi Ally,
>>
>> Sorry, I think I was unclear. I'd prefer these two initialized to NULL,
>> to match the other usages, over removing the __free() from them.
> 
> I had a patch for that already, but, isn't using __free discouraged in
> networking drivers [1]? Simon was against it [2]

you see, the construct is discouraged, so we don't use it everywhere,
but cleaning up just a little would not change the state of the matter
(IOW we will still be in "driver has some __free() usage" state).

TBH, I would not spent my time "undoing" all of the __free() that we
have already, especially the testing part sounds not fun.

Turning all usage points to "= NULL" is orthogonal, and would be great.

> 
> [2] https://lore.kernel.org/all/aQ9xp9pchMwml30P@horms.kernel.org/
> [1] https://docs.kernel.org/process/maintainer-netdev.html#using-device-managed-and-cleanup-h-constructs
> 
> Regards,
> Ally
>