linux-kernel - [PATCH] RTC: Fix infinite loop in initializing the alarm.

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Date:	Tue,  8 Apr 2014 00:54:42 +0200
From:	Ales Novak <alnovak@...e.cz>
To:	Alessandro Zummo <a.zummo@...ertech.it>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	rtc-linux@...glegroups.com, linux-kernel@...r.kernel.org,
	Jiri Kosina <jkosina@...e.cz>,
	John Stultz <john.stultz@...aro.org>,
	Ales Novak <alnovak@...e.cz>
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 <alnovak@...e.cz>
---
 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

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