rtc_time_to_tm: fix signed/unsigned arithmetic

commit 73442daf2ea85e2a779396b76b1a39b10188ecb5 upstream

commit 945185a69daa457c4c5e46e47f4afad7dcea734f ("rtc: rtc_time_to_tm: use
unsigned arithmetic") changed the some types in rtc_time_to_tm() to
unsigned:

 void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
 {
-       register int days, month, year;
+       unsigned int days, month, year;

This doesn't work for all cases, because days is checked for < 0 later
on:

if (days < 0) {
	year -= 1;
	days += 365 + LEAP_YEAR(year);
}

I think the correct fix would be to keep days signed and do an appropriate
cast later on.

Signed-off-by: Jan Altenberg <jan.altenberg@linutronix.de>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Cc: Dmitri Vorobiev <dmitri.vorobiev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/rtc/rtc-lib.c b/drivers/rtc/rtc-lib.c
index 9f996ec881ce90dbf2a97cef5ecb73e090d634c7..dd70bf73ce9d5e3dd5fa1686c12f1c46421b5624 100644 (file)
--- a/drivers/rtc/rtc-lib.c
+++ b/drivers/rtc/rtc-lib.c
@@ -51,10 +51,11 @@ EXPORT_SYMBOL(rtc_year_days);
  */
 void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
 {
-       unsigned int days, month, year;
+       unsigned int month, year;
+       int days;
 
        days = time / 86400;
-       time -= days * 86400;
+       time -= (unsigned int) days * 86400;
 
        /* day of the week, 1970-01-01 was a Thursday */
        tm->tm_wday = (days + 4) % 7;