lkml.org 
[lkml]   [2017]   [Aug]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v2] [BUGFIX] gpio: reject invalid gpio before getting gpio_desc
On Mon, Jul 31, 2017 at 4:57 AM, Masami Hiramatsu <mhiramat@kernel.org> wrote:
> Check user-given gpio number and reject it before
> calling gpio_to_desc() because gpio_to_desc() is
> for kernel driver and it expects given gpio number
> is valid (means 0 to 511).
> If given number is invalid, gpio_to_desc() calls
> WARN() and dump registers and stack for debug.
> This means user can easily kick WARN() just by
> writing invalid gpio number (e.g. 512) to
> /sys/class/gpio/export.
>

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

(2 bikesheds below)

> Fixes: 0e9a5edf5d01 ("gpio: fix deferred probe detection for legacy API")
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
> Changes in v2:
> - Add gpio_to_valid_desc() according to Andy's comment (Thanks!).
> - Fix patch description.
> ---
> drivers/gpio/gpiolib-sysfs.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
> index 4b44dd97c07f..819f36258925 100644
> --- a/drivers/gpio/gpiolib-sysfs.c
> +++ b/drivers/gpio/gpiolib-sysfs.c
> @@ -2,6 +2,7 @@
> #include <linux/mutex.h>
> #include <linux/device.h>
> #include <linux/sysfs.h>
> +#include <linux/gpio.h>
> #include <linux/gpio/consumer.h>
> #include <linux/gpio/driver.h>
> #include <linux/interrupt.h>
> @@ -432,6 +433,11 @@ static struct attribute *gpiochip_attrs[] = {
> };
> ATTRIBUTE_GROUPS(gpiochip);
>
> +static struct gpio_desc *gpio_to_valid_desc(int gpio)
> +{
> + return gpio_is_valid(gpio) ? gpio_to_desc(gpio) : NULL;
> +}
> +
> /*
> * /sys/class/gpio/export ... write-only
> * integer N ... number of GPIO to export (full access)
> @@ -450,7 +456,8 @@ static ssize_t export_store(struct class *class,
> if (status < 0)
> goto done;
>
> - desc = gpio_to_desc(gpio);
> + desc = gpio_to_valid_desc(gpio);

> +

No need, if you wish better to put modified line after comment.

> /* reject invalid GPIOs */
> if (!desc) {
> pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
> @@ -492,7 +499,8 @@ static ssize_t unexport_store(struct class *class,
> if (status < 0)
> goto done;
>
> - desc = gpio_to_desc(gpio);
> + desc = gpio_to_valid_desc(gpio);

> +


Ditto.

> /* reject bogus commands (gpio_unexport ignores them) */
> if (!desc) {
> pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
>



--
With Best Regards,
Andy Shevchenko

\
 
 \ /
  Last update: 2017-08-01 13:10    [W:0.071 / U:1.968 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site