From: Riwen Lu <luriwen@kylinos.cn>
Date: Thu, 6 Jan 2022 08:46:09 +0000 (+0800)
Subject: rtc: cmos: Evaluate century appropriate
X-Git-Tag: v4.19.228~4
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=3bee94e261cd3f592867c770056a4ef453d831e0;p=users%2Fdwmw2%2Flinux.git

rtc: cmos: Evaluate century appropriate

commit ff164ae39b82ee483b24579c8e22a13a8ce5bd04 upstream.

There's limiting the year to 2069. When setting the rtc year to 2070,
reading it returns 1970. Evaluate century starting from 19 to count the
correct year.

$ sudo date -s 20700106
Mon 06 Jan 2070 12:00:00 AM CST
$ sudo hwclock -w
$ sudo hwclock -r
1970-01-06 12:00:49.604968+08:00

Fixes: 2a4daadd4d3e5071 ("rtc: cmos: ignore bogus century byte")

Signed-off-by: Riwen Lu <luriwen@kylinos.cn>
Acked-by: Eric Wong <e@80x24.org>
Reviewed-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220106084609.1223688-1-luriwen@kylinos.cn
Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl> # preparation for stable
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c
index 18a6f15e313d8..86b8858917b62 100644
--- a/drivers/rtc/rtc-mc146818-lib.c
+++ b/drivers/rtc/rtc-mc146818-lib.c
@@ -82,7 +82,7 @@ unsigned int mc146818_get_time(struct rtc_time *time)
 	time->tm_year += real_year - 72;
 #endif
 
-	if (century > 20)
+	if (century > 19)
 		time->tm_year += (century - 19) * 100;
 
 	/*