linux-kernel - Re: [PATCH 1/2] gpio: sim: dispose of irq mappings before destroying the irq

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Date:   Tue, 22 Aug 2023 14:16:44 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Kent Gibson <warthog618@...il.com>, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH 1/2] gpio: sim: dispose of irq mappings before destroying
 the irq_sim domain

On Tue, Aug 22, 2023 at 2:12 PM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> On Tue, Aug 22, 2023 at 09:51:21AM +0200, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> >
> > If a GPIO simulator device is unbound with interrupts still requested,
> > we will hit a use-after-free issue in __irq_domain_deactivate_irq(). The
> > owner of the irq domain must dispose of all mappings before destroying
> > the domain object.
>
> ...
>
> > +static void gpio_sim_dispose_mappings(void *data)
> > +{
> > +     struct gpio_sim_chip *chip = data;
> > +     unsigned int i, irq;
> > +
> > +     for (i = 0; i < chip->gc.ngpio; i++) {
> > +             irq = irq_find_mapping(chip->irq_sim, i);
>
> > +             if (irq)
>
> This duplicates check in the following call.
>

Ah so it can be a direct call:

    irq_dispose_mapping(irq_find_mapping(chip->irq_sim, i));

?

Bart

> > +                     irq_dispose_mapping(irq);
> > +     }
> > +}
>
> --
> With Best Regards,
> Andy Shevchenko
>
>