linux-kernel - Re: backlight: catch invalid input

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Message-ID: <20081122203151.GA1856@elf.ucw.cz>
Date:	Sat, 22 Nov 2008 21:31:51 +0100
From:	Pavel Machek <pavel@...e.cz>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	rpurdie@...ys.net, linux-kernel@...r.kernel.org
Subject: Re: backlight: catch invalid input


Andrew hinted that strict_strtoul is right fix. Check input properly
in backlight, echo > brightness should not turn off the backlight.

Signed-off-by: Pavel Machek <pavel@...e.cz>

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 5c2e23d..e4c93fc 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -80,22 +80,18 @@ static ssize_t backlight_show_power(stru
 static ssize_t backlight_store_power(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t count)
 {
-	int rc = -ENXIO;
-	char *endp;
+	int rc;
 	struct backlight_device *bd = to_backlight_device(dev);
-	int power = simple_strtoul(buf, &endp, 0);
-	size_t size = endp - buf;
+	unsigned long power;
 
-	if (!size)
-		return -EINVAL;
-	if (*endp && isspace(*endp))
-		size++;
-	if (size != count)
-		return -EINVAL;
+	rc = strict_strtoul(buf, 0, &power);
+	if (rc)
+		return rc;
 
+	rc = -ENXIO;
 	mutex_lock(&bd->ops_lock);
 	if (bd->ops) {
-		pr_debug("backlight: set power to %d\n", power);
+		pr_debug("backlight: set power to %lu\n", power);
 		if (bd->props.power != power) {
 			bd->props.power = power;
 			backlight_update_status(bd);
@@ -118,23 +114,22 @@ static ssize_t backlight_show_brightness
 static ssize_t backlight_store_brightness(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t count)
 {
-	int rc = -ENXIO;
-	char *endp;
+	int rc;
 	struct backlight_device *bd = to_backlight_device(dev);
-	int brightness = simple_strtoul(buf, &endp, 0);
-	size_t size = endp - buf;
+	unsigned long brightness;
+
+ 	rc = strict_strtoul(buf, 0, &brightness);
+	if (rc)
+		return rc;
 
-	if (*endp && isspace(*endp))
-		size++;
-	if (size != count)
-		return -EINVAL;
+	rc = -ENXIO;
 
 	mutex_lock(&bd->ops_lock);
 	if (bd->ops) {
 		if (brightness > bd->props.max_brightness)
 			rc = -EINVAL;
 		else {
-			pr_debug("backlight: set brightness to %d\n",
+			pr_debug("backlight: set brightness to %lu\n",
 				 brightness);
 			if (bd->props.brightness != brightness) {
 				bd->props.brightness = brightness;


-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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