backlight: Catch invalid input in sysfs attributes

Check input properly in backlight, echo > brightness should not turn off
the backlight.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix printk warning]
Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

1 files changed, 15 insertions, 18 deletions

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 0664fc032235..9593fdc042f7 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -80,20 +80,18 @@ static ssize_t backlight_show_power(struct device *dev,
 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 (*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);
@@ -116,23 +114,22 @@ static ssize_t backlight_show_brightness(struct device *dev,
 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;