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Commit 36d46cdb authored by Baolin Wang's avatar Baolin Wang Committed by Alexandre Belloni
Browse files

rtc: Fix overflow when converting time64_t to rtc_time 



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: default avatarBaolin Wang <baolin.wang@linaro.org>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
parent 29a1f599

drivers/rtc/rtc-lib.c

+2 −4
Original line number Diff line number Diff line
@@ -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;