wakeup: Add the guard condition for len in pm_get_active_wakeup_sources

Check if the len is not greater than maximum to prevent buffer overflow.

Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>
Change-Id: I575b0a72bb5448b68353408d71fa8b83420c9088

drivers/base/power/wakeup.c

@@ -677,7 +677,7 @@ void pm_get_active_wakeup_sources(char *pending_wakeup_source, size_t max)
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(ws, &wakeup_sources, entry) {
-		if (ws->active) {
+		if (ws->active && len < max) {
 			if (!active)
 				len += scnprintf(pending_wakeup_source, max,
 						"Pending Wakeup Sources: ");