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Commit 90b05b05 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Linus Walleij
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gpio: reject invalid gpio before getting gpio_desc 



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.

Fixes: 0e9a5edf ("gpio: fix deferred probe detection for legacy API")
Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent ef954844

drivers/gpio/gpiolib-sysfs.c

+8 −2
Original line number Diff line number Diff line
@@ -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 +456,7 @@ static ssize_t export_store(struct class *class, 
	if (status < 0)

		goto done;



	desc = gpio_to_desc(gpio);

	desc = gpio_to_valid_desc(gpio);

	/* reject invalid GPIOs */

	if (!desc) {

		pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
@@ -493,7 +499,7 @@ static ssize_t unexport_store(struct class *class, 
	if (status < 0)

		goto done;



	desc = gpio_to_desc(gpio);

	desc = gpio_to_valid_desc(gpio);

	/* reject bogus commands (gpio_unexport ignores them) */

	if (!desc) {

		pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);