* Re: backlight: catch invalid input
2008-11-21 23:54 ` Andrew Morton
@ 2008-11-22 10:37 ` Pavel Machek
2008-11-22 20:31 ` Pavel Machek
1 sibling, 0 replies; 4+ messages in thread
From: Pavel Machek @ 2008-11-22 10:37 UTC (permalink / raw)
To: Andrew Morton; +Cc: rpurdie, linux-kernel
On Fri 2008-11-21 15:54:21, Andrew Morton wrote:
> On Fri, 21 Nov 2008 12:14:14 +0100
> Pavel Machek <pavel@suse.cz> wrote:
>
> >
> > Currently, echo > brightness turns brightness to zero due to
> > insufficient checking. Add a test to catch that.
> >
>
> OK. And what happens if you do
>
> echo wibble > brightness
>
> ?
That's okay, that is catched by tests already existing in there. size
is the size we decoded, count is how many bytes user wrote. If (size
!= count), we return failure.
But there's an exception for whitespace, and missing check for nothing
at all being written.
> > diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> > index fab0bc8..5c2e23d 100644
> > --- a/drivers/video/backlight/backlight.c
> > +++ b/drivers/video/backlight/backlight.c
> > @@ -86,6 +86,8 @@ static ssize_t backlight_store_power(str
> > int power = simple_strtoul(buf, &endp, 0);
> > size_t size = endp - buf;
> >
> > + if (!size)
> > + return -EINVAL;
> > if (*endp && isspace(*endp))
> > size++;
> > if (size != count)
>
> A better fix would be to use strict_strtoul() and check its return
> value.
Aha, here's the hint :-). Ok, will do.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: backlight: catch invalid input
2008-11-21 23:54 ` Andrew Morton
2008-11-22 10:37 ` Pavel Machek
@ 2008-11-22 20:31 ` Pavel Machek
1 sibling, 0 replies; 4+ messages in thread
From: Pavel Machek @ 2008-11-22 20:31 UTC (permalink / raw)
To: Andrew Morton; +Cc: rpurdie, linux-kernel
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@suse.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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