From: Riwen Lu luriwen@kylinos.cn

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 --- drivers/rtc/rtc-mc146818-lib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

Hello,

I have prepared this patch for inclusion into stable. Run-tested on top of 5.16.7 and 4.9.299, works as intended.

Greetings, Mateusz

diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c index dcfaf09946ee..2065842f775d 100644 --- a/drivers/rtc/rtc-mc146818-lib.c +++ b/drivers/rtc/rtc-mc146818-lib.c @@ -104,7 +104,7 @@ 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;

/*