gpio: GPIO_GET_CHIPINFO_IOCTL: Fix information leak

commit 0f4bbb233743bdfd51d47688b0bc2561f310488b upstream.

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.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 44d976c238c16a5fb527be8c39fd760a152bf422..6c443ddedb38b478cd9ea584adfeb8feef98f658 100644 (file)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -821,6 +821,8 @@ 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';