Commit e8ba8a2b authored by Yongliang Gao's avatar Yongliang Gao Committed by Alexandre Belloni
Browse files

rtc: check if __rtc_read_time was successful in rtc_timer_do_work() 



If the __rtc_read_time call fails,, the struct rtc_time tm; may contain
uninitialized data, or an illegal date/time read from the RTC hardware.

When calling rtc_tm_to_ktime later, the result may be a very large value
(possibly KTIME_MAX). If there are periodic timers in rtc->timerqueue,
they will continually expire, may causing kernel softlockup.

Fixes: 6610e089 ("RTC: Rework RTC code to use timerqueue for events")
Signed-off-by: default avatarYongliang Gao <leonylgao@tencent.com>
Acked-by: default avatarJingqun Li <jingqunli@tencent.com>
Link: https://lore.kernel.org/r/20241011043153.3788112-1-leonylgao@gmail.com


Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
parent 00f1bb9b

drivers/rtc/interface.c

+6 −1
Original line number Diff line number Diff line
@@ -904,13 +904,18 @@ void rtc_timer_do_work(struct work_struct *work) 
	struct timerqueue_node *next;

	ktime_t now;

	struct rtc_time tm;

	int err;



	struct rtc_device *rtc =

		container_of(work, struct rtc_device, irqwork);



	mutex_lock(&rtc->ops_lock);

again:

	__rtc_read_time(rtc, &tm);

	err = __rtc_read_time(rtc, &tm);

	if (err) {

		mutex_unlock(&rtc->ops_lock);

		return;

	}

	now = rtc_tm_to_ktime(tm);

	while ((next = timerqueue_getnext(&rtc->timerqueue))) {

		if (next->expires > now)