gpio: GPIO_GET_CHIPINFO_IOCTL: Fix information leak

The GPIO_GET_CHIPINFO_IOCTL handler allocates a gpiochip_info struct on the
stack and then passes it to copy_to_user(). But depending on the length of
the GPIO chip name and label the struct is only partially initialized.

This exposes the previous, potentially sensitive, stack content to the
issuing userspace application. To avoid this make sure that the struct is
fully initialized.

Cc: stable@vger.kernel.org
Fixes: 521a2ad6f862 ("gpio: add userspace ABI for GPIO line information")
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 dac975397253d5cbfae19652ef2fb3a82a84c54e..7a01969169e891682549b18831ff85bba12f9373 100644 (file)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -823,6 +823,8 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
        if (cmd == GPIO_GET_CHIPINFO_IOCTL) {
                struct gpiochip_info chipinfo;
 
+               memset(&chipinfo, 0, sizeof(chipinfo));
+
                strncpy(chipinfo.name, dev_name(&gdev->dev),
                        sizeof(chipinfo.name));
                chipinfo.name[sizeof(chipinfo.name)-1] = '\0';