| From 36d46cdb43efea74043e29e2a62b13e9aca31452 Mon Sep 17 00:00:00 2001 |
| From: Baolin Wang <baolin.wang@linaro.org> |
| Date: Mon, 25 Dec 2017 19:10:37 +0800 |
| Subject: rtc: Fix overflow when converting time64_t to rtc_time |
| |
| From: Baolin Wang <baolin.wang@linaro.org> |
| |
| commit 36d46cdb43efea74043e29e2a62b13e9aca31452 upstream. |
| |
| If we convert one large time values to rtc_time, in the original formula |
| 'days * 86400' can be overflowed in 'unsigned int' type to make the formula |
| get one incorrect remain seconds value. Thus we can use div_s64_rem() |
| function to avoid this situation. |
| |
| Signed-off-by: Baolin Wang <baolin.wang@linaro.org> |
| Acked-by: Arnd Bergmann <arnd@arndb.de> |
| Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> |
| Signed-off-by: Arnd Bergmann <arnd@arndb.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/rtc/rtc-lib.c | 6 ++---- |
| 1 file changed, 2 insertions(+), 4 deletions(-) |
| |
| --- a/drivers/rtc/rtc-lib.c |
| +++ b/drivers/rtc/rtc-lib.c |
| @@ -52,13 +52,11 @@ EXPORT_SYMBOL(rtc_year_days); |
| */ |
| void rtc_time64_to_tm(time64_t time, struct rtc_time *tm) |
| { |
| - unsigned int month, year; |
| - unsigned long secs; |
| + unsigned int month, year, secs; |
| int days; |
| |
| /* time must be positive */ |
| - days = div_s64(time, 86400); |
| - secs = time - (unsigned int) days * 86400; |
| + days = div_s64_rem(time, 86400, &secs); |
| |
| /* day of the week, 1970-01-01 was a Thursday */ |
| tm->tm_wday = (days + 4) % 7; |
