linux-kernel - Re: [PATCH 5.10] staging: gasket: interrupt: Clean interrupt

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Message-ID: <ba0ad96d-6515-66e3-e140-cd7c3999577e@astralinux.ru>
Date:   Tue, 16 May 2023 13:44:06 +0300
From:   Ekaterina Esina <eesina@...ralinux.ru>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Rob Springer <rspringer@...gle.com>,
        Todd Poynor <toddpoynor@...gle.com>,
        Ben Chan <benchan@...omium.org>, Richard Yeh <rcy@...gle.com>,
        John Joseph <jnjoseph@...gle.com>,
        Simon Que <sque@...omium.org>, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org, lvc-project@...uxtesting.org
Subject: Re: [PATCH 5.10] staging: gasket: interrupt: Clean interrupt_data
 after free



On 15.05.2023 16:02, Greg Kroah-Hartman wrote:
> On Mon, May 15, 2023 at 03:29:50PM +0300, Esina Ekaterina wrote:
>> Add interrupt_data = NULL after kfree(interrupt_data) in
>> gasket_interrupt_init. It is needed to avoid double free
>> in gasket_interrupt_cleanup, there is a check for NULL
>> before kfree(interrupt_data).
>>
>> Found by Astra Linux on behalf of Linux Verification Center
>> (linuxtesting.org) with SVACE.
>>
>> Fixes: 9a69f5087ccc ("drivers/staging: Gasket driver framework + Apex driver")
>> Signed-off-by: Esina Ekaterina <eesina@...ralinux.ru>
>> ---
>>   drivers/staging/gasket/gasket_interrupt.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/staging/gasket/gasket_interrupt.c b/drivers/staging/gasket/gasket_interrupt.c
>> index 864342acfd86..48b664b9134a 100644
>> --- a/drivers/staging/gasket/gasket_interrupt.c
>> +++ b/drivers/staging/gasket/gasket_interrupt.c
>> @@ -337,6 +337,7 @@ int gasket_interrupt_init(struct gasket_dev *gasket_dev)
>>   			sizeof(*interrupt_data->eventfd_ctxs), GFP_KERNEL);
>>   	if (!interrupt_data->eventfd_ctxs) {
>>   		kfree(interrupt_data);
>> +		interrupt_data = NULL;
>>   		return -ENOMEM;
>>   	}
>>   
>> @@ -346,6 +347,7 @@ int gasket_interrupt_init(struct gasket_dev *gasket_dev)
>>   	if (!interrupt_data->interrupt_counts) {
>>   		kfree(interrupt_data->eventfd_ctxs);
>>   		kfree(interrupt_data);
>> +		interrupt_data = NULL;
>>   		return -ENOMEM;
>>   	}
>>   
>> -- 
>> 2.40.1
> 
> Also, your tool is wrong, this is not a correct fix at all.
> 
> How did you test it?  Why is your tool spitting out incorrect code?  Why
> are you not verifying it's output before asking others to do so?
> 
> Please don't do this anymore, it's wasteful on our side, right?  Please
> take the time to review existing changes for problems, that would be
> more useful overall to everyone.
> 
> thanks,
> 
> greg k-h

I apologize, there is a mistake. It should've been 
gasket_dev->interrupt_data = NULL istead of interrupt_data = NULL

Best regards,
Ekaterina Esina