4.14-stable review patch. If anyone has any objections, please let me know.
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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;