linux-kernel - Re: [PATCH] misc: microchip: pci1xxxx: Fix possible double free in error handling path

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <81b7066b-f769-4897-aa8e-8a1391894877@wanadoo.fr>
Date: Tue, 7 Jan 2025 18:42:09 +0100
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Ma Ke <make24@...as.ac.cn>
Cc: arnd@...db.de, gregkh@...uxfoundation.org,
 kumaravel.thiagarajan@...rochip.com, linux-gpio@...r.kernel.org,
 linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] misc: microchip: pci1xxxx: Fix possible double free in
 error handling path

Le 07/01/2025 à 02:19, Ma Ke a écrit :
> Christophe JAILLET<christophe.jaillet@...adoo.fr> wrote:
>> Ma Ke <make24@...as.ac.cn> writes:
>>> When auxiliary_device_add() returns error and then calls
>>> auxiliary_device_uninit(), the callback function
>>> gp_auxiliary_device_release() calls kfree() to free memory. Do not
>>> call kfree() again in the error handling path.
>>>
>>> Fix this by skipping the redundant kfree().
>>>
>>> Found by code review.
>>>
>>> Cc: stable@...r.kernel.org
>>> Fixes: 393fc2f5948f ("misc: microchip: pci1xxxx: load auxiliary bus driver for the PIO function in the multi-function endpoint of pci1xxxx device.")
>>> Signed-off-by: Ma Ke <make24@...as.ac.cn>
>>> ---
>>>    drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_gp.c | 2 ++
>>>    1 file changed, 2 insertions(+)
>>>
>>> diff --git a/drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_gp.c b/drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_gp.c
>>> index 32af2b14ff34..fbd712938bdc 100644
>>> --- a/drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_gp.c
>>> +++ b/drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_gp.c
>>> @@ -111,6 +111,7 @@ static int gp_aux_bus_probe(struct pci_dev *pdev, const struct pci_device_id *id
>>>    
>>>    err_aux_dev_add_1:
>>>    	auxiliary_device_uninit(&aux_bus->aux_device_wrapper[1]->aux_dev);
>>> +	goto err_aux_dev_add_0;
>>>    
>>>    err_aux_dev_init_1:
>>>    	ida_free(&gp_client_ida, aux_bus->aux_device_wrapper[1]->aux_dev.id);
>>> @@ -120,6 +121,7 @@ static int gp_aux_bus_probe(struct pci_dev *pdev, const struct pci_device_id *id
>>>    
>>>    err_aux_dev_add_0:
>>>    	auxiliary_device_uninit(&aux_bus->aux_device_wrapper[0]->aux_dev);
>>> +	goto err_ret;
>>>    
>>>    err_aux_dev_init_0:
>>>    	ida_free(&gp_client_ida, aux_bus->aux_device_wrapper[0]->aux_dev.id);
>>
>> Hi,
>>
>> This is strange because the nearly same patch is in -next since June
>> 2024 ([1])
>>
>> It is also in Linux since at least 6.10 ([2])
>>
>> In [1] and [2], there is also a new err_ret label, which is not part of
>> your patch.
>>
>> On which tree are you working?
>> Is your patch compile tested?
>>
>> CJ
> 
> Thank you for your response. I discovered the aforementioned bug in
> Linux kernel v6.4.16 (the latest v6.4). It appears that the fix was
> not completed in the latest version of v6.4. I have also checked the
> link you mentioned and saw that the issue has been fixed in v6.10. I
> realize that I omitted the final jump patch in the patch v1 submitted,
> and I will perfect it in patch v2. Thank you for your suggestion.

v6.4 is not supported any more, so an updated patch would never be applied.
See active branches on https://www.kernel.org/.

Anyway, when don't working on a recent tree, you should tell it, because 
no one can guess that your patch is related to something old.

 > I realize that I omitted the final jump

So I guess, that you not compile tested your patch.
You should never do that, event when the change looks trivial.

CJ