forked from luck/tmp_suning_uos_patched
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>
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@ -36,26 +36,28 @@ static int fb_notifier_callback(struct notifier_block *p,
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struct bl_trig_notifier, notifier);
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struct led_classdev *led = n->led;
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struct fb_event *fb_event = data;
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int *blank = fb_event->data;
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int new_status = *blank ? BLANK : UNBLANK;
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int *blank;
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int new_status;
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switch (event) {
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case FB_EVENT_BLANK:
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if (new_status == n->old_status)
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break;
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/* If we aren't interested in this event, skip it immediately ... */
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if (event != FB_EVENT_BLANK)
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return 0;
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if ((n->old_status == UNBLANK) ^ n->invert) {
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n->brightness = led->brightness;
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__led_set_brightness(led, LED_OFF);
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} else {
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__led_set_brightness(led, n->brightness);
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}
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blank = fb_event->data;
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new_status = *blank ? BLANK : UNBLANK;
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n->old_status = new_status;
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if (new_status == n->old_status)
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return 0;
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break;
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if ((n->old_status == UNBLANK) ^ n->invert) {
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n->brightness = led->brightness;
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__led_set_brightness(led, LED_OFF);
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} else {
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__led_set_brightness(led, n->brightness);
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}
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n->old_status = new_status;
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return 0;
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}
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