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| author | Manfred Schlaegl <manfred.schlaegl@gmx.at> | 2013-08-13 13:17:05 +0200 |
|---|---|---|
| committer | Bryan Wu <cooloney@gmail.com> | 2013-08-27 02:46:36 +0200 |
| commit | c945cbcf453cb72dc2287fc4f7b63314f173b313 (patch) | |
| tree | dd65b5b53670ce33b476ad15a470e9240b032ab7 | |
| parent | leds-pca963x: Fix device tree parsing (diff) | |
| download | linux-c945cbcf453cb72dc2287fc4f7b63314f173b313.tar.xz linux-c945cbcf453cb72dc2287fc4f7b63314f173b313.zip | |
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>
| -rw-r--r-- | drivers/leds/trigger/ledtrig-backlight.c | 30 |
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; } |