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authorManfred Schlaegl <manfred.schlaegl@gmx.at>2013-08-13 04:17:05 -0700
committerBryan Wu <cooloney@gmail.com>2013-08-26 17:46:36 -0700
commitc945cbcf453cb72dc2287fc4f7b63314f173b313 (patch)
treedd65b5b53670ce33b476ad15a470e9240b032ab7 /drivers/leds
parent8a6acd648c1dfdc82f1bbcd15f7777962054c268 (diff)
leds: trigger: ledtrig-backlight: Fix invalid memory access in fb_event notification callback
fb_notifier_callback is called on any event fired by fb_notifier_call_chain. Events may, or may not contain some data (fb_event.data). In case of FB_EVENT_BLANK fb_event.data contains a pointer to an integer holdingthe blank state. The Problem is, that in ledtrig-backlight.c - fb_notifier_callback the pointer to blank state is dereferenced BEFORE the event-type is checked. Obviously this leads to problems with other events than FB_EVENT_BLANK, where fb_event.data is undefined or NULL. It seems, that this problem existed ever since the driver was added. Like in drivers/video/backlight/backlight.c line 43 I would suggest to return immediately on events other than FB_EVENT_BLANK. Signed-off-by: Manfred Schlaegl <manfred.schlaegl@gmx.at> Signed-off-by: Bryan Wu <cooloney@gmail.com>
Diffstat (limited to 'drivers/leds')
-rw-r--r--drivers/leds/trigger/ledtrig-backlight.c30
1 files changed, 16 insertions, 14 deletions
diff --git a/drivers/leds/trigger/ledtrig-backlight.c b/drivers/leds/trigger/ledtrig-backlight.c
index 3c9c88a07eb8..47e55aa9eefa 100644
--- a/drivers/leds/trigger/ledtrig-backlight.c
+++ b/drivers/leds/trigger/ledtrig-backlight.c
@@ -36,26 +36,28 @@ static int fb_notifier_callback(struct notifier_block *p,
struct bl_trig_notifier, notifier);
struct led_classdev *led = n->led;
struct fb_event *fb_event = data;
- int *blank = fb_event->data;
- int new_status = *blank ? BLANK : UNBLANK;
+ int *blank;
+ int new_status;
- switch (event) {
- case FB_EVENT_BLANK:
- if (new_status == n->old_status)
- break;
+ /* If we aren't interested in this event, skip it immediately ... */
+ if (event != FB_EVENT_BLANK)
+ return 0;
- if ((n->old_status == UNBLANK) ^ n->invert) {
- n->brightness = led->brightness;
- __led_set_brightness(led, LED_OFF);
- } else {
- __led_set_brightness(led, n->brightness);
- }
+ blank = fb_event->data;
+ new_status = *blank ? BLANK : UNBLANK;
- n->old_status = new_status;
+ if (new_status == n->old_status)
+ return 0;
- break;
+ if ((n->old_status == UNBLANK) ^ n->invert) {
+ n->brightness = led->brightness;
+ __led_set_brightness(led, LED_OFF);
+ } else {
+ __led_set_brightness(led, n->brightness);
}
+ n->old_status = new_status;
+
return 0;
}