gpio: GPIO_GET_LINEHANDLE_IOCTL: Validate line offset

The line offset that is used as an index into the descs array is provided
by userspace and might go beyond the bounds of the array. If that happens
undefined behavior will occur.

Make sure that the offset is within the bounds of the desc array and reject
any requests that specify a value outside of it.

Cc: stable@vger.kernel.org
Fixes: d7c51b47ac11 ("gpio: userspace ABI for reading/writing GPIO lines")
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 7a01969169e891682549b18831ff85bba12f9373..d287cb4e97c4bac4faedf152affd30a85b4b31ce 100644 (file)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -444,6 +444,11 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
                u32 lflags = handlereq.flags;
                struct gpio_desc *desc;
 
+               if (offset >= gdev->ngpio) {
+                       ret = -EINVAL;
+                       goto out_free_descs;
+               }
+
                desc = &gdev->descs[offset];
                ret = gpiod_request(desc, lh->label);
                if (ret)