Re: [PATCH] PCI: endpoint: Fix configfs group removal on driver teardown

[Damien Le Moal <dlemoal@kernel.org>]

On 6/23/25 10:35 PM, Niklas Cassel wrote:
> On Mon, Jun 23, 2025 at 09:01:53PM +0900, Damien Le Moal wrote:
>> On 6/23/25 19:00, Niklas Cassel wrote:
>>>
>>> I think it is a litte bit confusing that you attach a KASAN
>>> splat to a patch that fixes two different bugs.
>>>
>>> Surely this KASAN bug can be fixes with only:
>>>
>>> -     list_del(&driver->epf_group);
>>> +     WARN_ON(!list_empty(&driver->epf_group));
>>
>> Yes, with that, you will not get the KASAN warning, but you will get the
>> WARN_ON() to trigger unless bug #1 is applied first. But if you apply #1 first,
>> then any testing done with that bug fix only will trigger a NULL pointer
>> de-reference on the list_del().
> 
> Ok, let me rephrase :)
> 
> Surely this KASAN bug can be fixed with only:
> 
> -     list_del(&driver->epf_group);
> 
> As the bug is that the code is trying to delete a list head, which is just
> wrong.
> 
> 
> A patch 2/2 could add a list_del() to pci_ep_cfs_remove_epf_group() and the
> WARN_ON() to pci_epf_remove_cfs().
> 
> Considering that pci_ep_cfs_remove_epf_group() also frees the memory for
> the group, I think it is more correct to use list_del() rather than
> list_del_init(), as no one will be able to re-use this group after calling
> pci_ep_cfs_remove_epf_group() on it.

OK. Sending v2.


-- 
Damien Le Moal
Western Digital Research