linux-kernel - [PATCH resend] rtc: Fix alarm rollover when day or month is out-of-range

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Date:	Fri, 30 Dec 2011 18:35:52 -0600
From:	Jonathan Nieder <jrnieder@...il.com>
To:	"P." <mailme667@...oo.co.uk>
Cc:	rtc-linux@...glegroups.com, linux-kernel@...r.kernel.org,
	Alessandro Zummo <a.zummo@...ertech.it>,
	John Stultz <john.stultz@...aro.org>,
	Ben Hutchings <ben@...adent.org.uk>
Subject: [PATCH resend] rtc: Fix alarm rollover when day or month is
 out-of-range

From: Ben Hutchings <ben@...adent.org.uk>
Date: Thu, 29 Dec 2011 16:41:56 +0100

Commit f44f7f96a20a ('RTC: Initialize kernel state from RTC')
introduced a potential infinite loop.  If an alarm time contains a
wildcard month and an invalid day (> 31), or a wildcard year and an
invalid month (>= 12), the loop searching for the next matching date
will never terminate.  Treat the invalid values as wildcards.

Fixes <http://bugs.debian.org/646429>, <http://bugs.debian.org/653331>

Reported-by: leo weppelman <leoweppelman@...glemail.com>
Reported-by: "P. van Gaans" <mailme667@...oo.co.uk>
Cc: stable@...r.kernel.org
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Signed-off-by: Jonathan Nieder <jrnieder@...il.com>
---
P. wrote:

> Following the advice from Jonathan Nieder I am sending this mail.

Old advice. :)

Here's a patch that was sent to the rtc-linux list, but I can't
seem to find it with search.gmane.org.

 drivers/rtc/interface.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index 3bcc7cfcaba7..67b68c4543d0 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -232,11 +232,11 @@ int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 		alarm->time.tm_hour = now.tm_hour;
 
 	/* For simplicity, only support date rollover for now */
-	if (alarm->time.tm_mday == -1) {
+	if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
 		alarm->time.tm_mday = now.tm_mday;
 		missing = day;
 	}
-	if (alarm->time.tm_mon == -1) {
+	if ((unsigned)alarm->time.tm_mon >= 12) {
 		alarm->time.tm_mon = now.tm_mon;
 		if (missing == none)
 			missing = month;
-- 
1.7.8.2+next.20111228

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