linux-kernel - Re: [PATCH] gpiolib: sanitize flags before allocating memory in lineevent

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Message-ID: <CAMRc=MdrWRgGAdHdKKo2T=A4+Q0+kxwRgLSx+xWurnn9qD0yMA@mail.gmail.com>
Date:   Tue, 1 Oct 2019 12:08:06 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: Re: [PATCH] gpiolib: sanitize flags before allocating memory in lineevent_create()

pon., 16 wrz 2019 o 11:46 Bartosz Golaszewski <brgl@...ev.pl> napisał(a):
>
> From: Bartosz Golaszewski <bgolaszewski@...libre.com>
>
> Move all the flags sanitization before any memory allocation in
> lineevent_create() in order to remove a couple unneeded gotos.
>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
> ---
>  drivers/gpio/gpiolib.c | 42 ++++++++++++++++++------------------------
>  1 file changed, 18 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index d9074191edef..194b0bcdcfb7 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -899,6 +899,24 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
>
>         if (copy_from_user(&eventreq, ip, sizeof(eventreq)))
>                 return -EFAULT;
> +
> +       offset = eventreq.lineoffset;
> +       lflags = eventreq.handleflags;
> +       eflags = eventreq.eventflags;
> +
> +       if (offset >= gdev->ngpio)
> +               return -EINVAL;
> +
> +       /* Return an error if a unknown flag is set */
> +       if ((lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) ||
> +           (eflags & ~GPIOEVENT_REQUEST_VALID_FLAGS))
> +               return -EINVAL;
> +
> +       /* This is just wrong: we don't look for events on output lines */
> +       if ((lflags & GPIOHANDLE_REQUEST_OUTPUT) ||
> +           (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
> +           (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE))
> +               return -EINVAL;
>
>         le = kzalloc(sizeof(*le), GFP_KERNEL);
>         if (!le)
> @@ -917,30 +935,6 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
>                 }
>         }
>
> -       offset = eventreq.lineoffset;
> -       lflags = eventreq.handleflags;
> -       eflags = eventreq.eventflags;
> -
> -       if (offset >= gdev->ngpio) {
> -               ret = -EINVAL;
> -               goto out_free_label;
> -       }
> -
> -       /* Return an error if a unknown flag is set */
> -       if ((lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) ||
> -           (eflags & ~GPIOEVENT_REQUEST_VALID_FLAGS)) {
> -               ret = -EINVAL;
> -               goto out_free_label;
> -       }
> -
> -       /* This is just wrong: we don't look for events on output lines */
> -       if ((lflags & GPIOHANDLE_REQUEST_OUTPUT) ||
> -           (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
> -           (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)) {
> -               ret = -EINVAL;
> -               goto out_free_label;
> -       }
> -
>         desc = &gdev->descs[offset];
>         ret = gpiod_request(desc, le->label);
>         if (ret)
> --
> 2.21.0
>

Patch applied.

Bart