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mini2440: Fix bogus buffer access in LCD backlight driver

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The backlight driver always writes a bogus value
from memory into the LCD brightness register.

Fix it up by adding bounds checks and
use a more sane default value.

While looking at the code, I noticed
that BACKLIGHT_CONTROL_SET probably ignores
the desired brightness level, too.

Note: Please test on real hardware, I don't own it.

cppcheck reported:
[rockbox/firmware/target/arm/s3c2440/mini2440/backlight-mini2440.c:53]: (error) Array 'log_brightness[13]' accessed at index 255, which is out of bounds.

Change-Id: Iaafa929a8adaa97b93ebcb66e1f6bd3bf0dad84e
This commit is contained in:
Thomas Jarosch 2014-12-20 14:47:09 +01:00
parent d62e1b3c5f
commit 575ec8902e
1 changed files with 10 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

12
firmware/target/arm/s3c2440/mini2440/backlight-mini2440.c
View file

@ -48,6 +48,11 @@ static unsigned char backlight_target;
/* Assumes that the backlight has been initialized */
void _backlight_set_brightness(int brightness)
{
if (brightness < 0)
brightness = 0;
else if(brightness > MAX_BRIGHTNESS_SETTING)
brightness = MAX_BRIGHTNESS_SETTING;
/* stop the interrupt from messing us up */
backlight_control = BACKLIGHT_CONTROL_IDLE;
_backlight_brightness = log_brightness[brightness];
@ -85,11 +90,14 @@ static void led_control_service(void)
backlight_control = BACKLIGHT_CONTROL_IDLE;
break;
case BACKLIGHT_CONTROL_ON:
_backlight_set_brightness(255);
_backlight_set_brightness(DEFAULT_BRIGHTNESS_SETTING);
backlight_control = BACKLIGHT_CONTROL_IDLE;
break;
case BACKLIGHT_CONTROL_SET:
_backlight_set_brightness(255);
/* TODO: This is probably wrong since it sets a fixed value.
It was a fixed value of 255 before, but that was even more wrong
since it accessed the log_brightness buffer out of bounds */
_backlight_set_brightness(DEFAULT_BRIGHTNESS_SETTING);
backlight_control = BACKLIGHT_CONTROL_IDLE;
break;
case BACKLIGHT_CONTROL_FADE: