5.4-stable review patch. If anyone has any objections, please let me know.
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From: Yongliang Gao leonylgao@tencent.com
[ Upstream commit e8ba8a2bc4f60a1065f23d6a0e7cbea945a0f40d ]
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: 6610e0893b8b ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/rtc/interface.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c index d858cd819932f..1536d53a7af7f 100644 --- a/drivers/rtc/interface.c +++ b/drivers/rtc/interface.c @@ -894,13 +894,18 @@ 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)