gpio: handle compatible ioctl() pointers

If we're using the compatible ioctl() we need to handle the
argument pointer in a special way or there will be trouble.

Fixes: 3c702e9987e2 ("gpio: add a userspace chardev ABI for GPIOs")
Reported-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 13 insertions, 2 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index e901d2666b46..68dbff5d8f57 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -20,6 +20,7 @@
 #include <linux/cdev.h>
 #include <linux/fs.h>
 #include <linux/uaccess.h>
+#include <linux/compat.h>
 #include <uapi/linux/gpio.h>
 
 #include "gpiolib.h"
@@ -316,7 +317,7 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
         struct gpio_device *gdev = filp->private_data;
         struct gpio_chip *chip = gdev->chip;
-        int __user *ip = (int __user *)arg;
+        void __user *ip = (void __user *)arg;
 
         /* We fail any subsequent ioctl():s when the chip is gone */
         if (!chip)
@@ -388,6 +389,14 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
         return -EINVAL;
 }
 
+#ifdef CONFIG_COMPAT
+static long gpio_ioctl_compat(struct file *filp, unsigned int cmd,
+                              unsigned long arg)
+{
+        return gpio_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
+}
+#endif
+
 /**
  * gpio_chrdev_open() - open the chardev for ioctl operations
  * @inode: inode for this chardev
@@ -431,7 +440,9 @@ static const struct file_operations gpio_fileops = {
         .owner = THIS_MODULE,
         .llseek = noop_llseek,
         .unlocked_ioctl = gpio_ioctl,
-        .compat_ioctl = gpio_ioctl,
+#ifdef CONFIG_COMPAT
+        .compat_ioctl = gpio_ioctl_compat,
+#endif
 };
 
 static void gpiodevice_release(struct device *dev)