linux-kernel - Re: [PATCH v2] gpio: cdev: sanitize the label before requesting the interrupt

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Date: Fri, 22 Mar 2024 12:52:29 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Kent Gibson <warthog618@...il.com>
Cc: Linus Walleij <linus.walleij@...aro.org>, linux-gpio@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Alexey Dobriyan <adobriyan@...il.com>, stable@...r.kernel.org, 
	Stefan Wahren <wahrenst@....net>, Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v2] gpio: cdev: sanitize the label before requesting the interrupt

On Fri, Mar 22, 2024 at 12:18 PM Kent Gibson <warthog618@...il.com> wrote:
>
> On Fri, Mar 22, 2024 at 10:02:08AM +0100, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> >
> > @@ -2198,12 +2216,18 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
> >       if (ret)
> >               goto out_free_le;
> >
> > +     label = make_irq_label(le->label);
> > +     if (!label) {
> > +             ret = -ENOMEM;
> > +             goto out_free_le;
> > +     }
> > +
> >       /* Request a thread to read the events */
> >       ret = request_threaded_irq(irq,
> >                                  lineevent_irq_handler,
> >                                  lineevent_irq_thread,
> >                                  irqflags,
> > -                                le->label,
> > +                                label,
> >                                  le);
> >       if (ret)
> >               goto out_free_le;
>
> Leaks label if the request_threaded_irq() fails.
>

Ah, dammit, I didn't catch the fact that irq_free() will not return
the label address if the request failed.

Nice catch.

Bart