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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: 0e9a5edf5d ("gpio: fix deferred probe detection for legacy API")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Masami Hiramatsu 2017-08-02 13:47:42 +09:00 committed by Linus Walleij
parent ef954844c7
commit 90b05b0598
1 changed files with 8 additions and 2 deletions
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10
drivers/gpio/gpiolib-sysfs.c
View File

@ -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);