Re: [PATCH 5.10] staging: gasket: interrupt: Clean interrupt_data after free

[Ekaterina Esina]

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@xxxxxxxxxxxxx>
> > ---
> >   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