From 018ea3fea1c6a60778bb95004aa34e4f155d52ab Mon Sep 17 00:00:00 2001 From: Baolin Wang Date: Mon, 25 Dec 2017 19:10:37 +0800 Subject: rtc: Fix overflow when converting time64_t to rtc_time 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 Acked-by: Arnd Bergmann Signed-off-by: Alexandre Belloni Signed-off-by: Arnd Bergmann Signed-off-by: Greg Kroah-Hartman --- drivers/rtc/rtc-lib.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'drivers/rtc/rtc-lib.c') diff --git a/drivers/rtc/rtc-lib.c b/drivers/rtc/rtc-lib.c index e6bfb9c42a10..5b136bdc03d4 100644 --- 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; -- cgit v1.2.3