2014-04-07 22:54:50

by Ales Novak

Subject: [PATCH] RTC: Fix infinite loop in initializing the alarm.

In __rtc_read_alarm(), if the alarm time retrieved by
rtc_read_alarm_internal() from the device contains invalid values
(e.g. month=2,mday=31) and the year not set (=-1), the initialization
will loop infinitely because the year-fixing loop expects the
time being invalid due to leap year.

Fix reduces the loop to the leap years and adds final validity check.

Signed-off-by: Ales Novak <[email protected]>
---
drivers/rtc/interface.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index 544be72..a2df283 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -292,7 +292,9 @@ int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
do {
alarm->time.tm_year++;
- } while (rtc_valid_tm(&alarm->time) != 0);
+ } while (alarm->time.tm_mon == 1
+ && is_leap_year(alarm->time.tm_year + 1900)
+ && rtc_valid_tm(&alarm->time) != 0);
break;

default:
@@ -300,7 +302,16 @@ int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
}

done:
- return 0;
+ err = rtc_valid_tm(&alarm->time);
+
+ if (err) {
+ dev_warn(&rtc->dev, "invalid alarm value: %d-%d-%d %d:%d:%d\n",
+ alarm->time.tm_year + 1900, alarm->time.tm_mon + 1,
+ alarm->time.tm_mday, alarm->time.tm_hour, alarm->time.tm_min,
+ alarm->time.tm_sec);
+ }
+
+ return err;
}

int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
--
1.8.1.4

2014-04-08 14:43:11

by Alessandro Zummo

Subject: Re: [PATCH] RTC: Fix infinite loop in initializing the alarm.

On Tue, 8 Apr 2014 00:54:42 +0200
Ales Novak <[email protected]> wrote:

> In __rtc_read_alarm(), if the alarm time retrieved by
> rtc_read_alarm_internal() from the device contains invalid values
> (e.g. month=2,mday=31) and the year not set (=-1), the initialization
> will loop infinitely because the year-fixing loop expects the
> time being invalid due to leap year.
>
> Fix reduces the loop to the leap years and adds final validity check.
>
> Signed-off-by: Ales Novak <[email protected]>

Seems reasonable.

Acked-by: Alessandro Zummo <[email protected]>

--

Best regards,

Alessandro Zummo,
Tower Technologies - Torino, Italy

http://www.towertech.it