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rtc: check if __rtc_read_time was successful in rtc_timer_do_work()

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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: 6610e0893b ("RTC: Rework RTC code to use timerqueue for events")
Signed-off-by: Yongliang Gao <leonylgao@tencent.com>
Acked-by: Jingqun Li <jingqunli@tencent.com>
Link: https://lore.kernel.org/r/20241011043153.3788112-1-leonylgao@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Yongliang Gao 2024-10-11 12:31:53 +08:00 committed by Alexandre Belloni
parent 00f1bb9b84
commit e8ba8a2bc4
1 changed files with 6 additions and 1 deletions
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7
drivers/rtc/interface.c
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@ -904,13 +904,18 @@ void rtc_timer_do_work(struct work_struct *work)
struct timerqueue_node *next; struct timerqueue_node *next;
ktime_t now; ktime_t now;
struct rtc_time tm; struct rtc_time tm;
int err;
struct rtc_device *rtc = struct rtc_device *rtc =
container_of(work, struct rtc_device, irqwork); container_of(work, struct rtc_device, irqwork);
mutex_lock(&rtc->ops_lock); mutex_lock(&rtc->ops_lock);
again: 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); now = rtc_tm_to_ktime(tm);
while ((next = timerqueue_getnext(&rtc->timerqueue))) { while ((next = timerqueue_getnext(&rtc->timerqueue))) {
if (next->expires > now) if (next->expires > now)