On Tue, 1 Aug 2017 14:10:03 +0300
Andy Shevchenko [off-list ref] wrote:

On Mon, Jul 31, 2017 at 4:57 AM, Masami Hiramatsu [off-list ref] wrote:

quoted

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 <redacted>

(2 bikesheds below)

quoted

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);

quoted

+

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

OK, should I update the patch and resend?

Thanks,

quoted

        /* 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);

quoted

+

Ditto.

quoted

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

-- 
With Best Regards,
Andy Shevchenko

-- 
Masami Hiramatsu [off-list ref]