[PATCH] watchdog: gpio-wdt: be more strict about hw_algo matching

[PATCH] watchdog: gpio-wdt: be more strict about hw_algo matching

[Uwe Kleine-König]

strncmp(algo, "toggle", 6) doesn't compare the trailing '\0' byte, so
using

	hw_algo = "toggleboggle"

is recognized the same way as

	hw_algo = "toggle"

. While this doesn't introduce any problems for a device tree that
sticks to the documented settings it's still ugly.

Fix this by using strcmp to only match on "toggle" and "level".

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/watchdog/gpio_wdt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c
index 1687cc2d7122..57d30f1f55ab 100644
--- a/drivers/watchdog/gpio_wdt.c
+++ b/drivers/watchdog/gpio_wdt.c
@@ -182,10 +182,10 @@ static int gpio_wdt_probe(struct platform_device *pdev)
 	ret = of_property_read_string(pdev->dev.of_node, "hw_algo", &algo);
 	if (ret)
 		return ret;
-	if (!strncmp(algo, "toggle", 6)) {
+	if (!strcmp(algo, "toggle")) {
 		priv->hw_algo = HW_ALGO_TOGGLE;
 		f = GPIOF_IN;
-	} else if (!strncmp(algo, "level", 5)) {
+	} else if (!strcmp(algo, "level")) {
 		priv->hw_algo = HW_ALGO_LEVEL;
 		f = priv->active_low ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
 	} else {
-- 
2.1.4

Re: [PATCH] watchdog: gpio-wdt: be more strict about hw_algo matching

[Guenter Roeck]

On 07/30/2015 02:32 AM, Uwe Kleine-König wrote:
> strncmp(algo, "toggle", 6) doesn't compare the trailing '\0' byte, so
> using
>
> 	hw_algo = "toggleboggle"
>
> is recognized the same way as
>
> 	hw_algo = "toggle"
>
> . While this doesn't introduce any problems for a device tree that
> sticks to the documented settings it's still ugly.
>
> Fix this by using strcmp to only match on "toggle" and "level".
>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>