* [rtc-linux] re: rtc: fix overflow and incorrect calculation in rtc_time64_to_tm
@ 2016-01-05 9:57 Dan Carpenter
0 siblings, 0 replies; only message in thread
From: Dan Carpenter @ 2016-01-05 9:57 UTC (permalink / raw)
To: sasha.levin; +Cc: rtc-linux
Hello Sasha Levin,
The patch cab572b82c4b: "rtc: fix overflow and incorrect calculation
in rtc_time64_to_tm" from Dec 3, 2015, leads to the following static
checker warning:
drivers/rtc/rtc-lib.c:72 rtc_time64_to_tm()
warn: unsigned 'days' is never less than zero.
drivers/rtc/rtc-lib.c
49 /*
50 * rtc_time_to_tm64 - Converts time64_t to rtc_time.
51 * Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
52 */
53 void rtc_time64_to_tm(time64_t time, struct rtc_time *tm)
54 {
55 unsigned int month, year;
56 int secs;
57 unsigned long days;
^^^^^^^^^^^^^^^^^^^
58
59 /*
60 * time must be positive
61 * This will fail for 32bit platforms on January 21st 11761191
62 */
63 days = div_s64_rem(time, 86400, &secs);
64
65 /* day of the week, 1970-01-01 was a Thursday */
66 tm->tm_wday = (days + 4) % 7;
67
68 year = 1970 + days / 365;
69 days -= (year - 1970) * 365
70 + LEAPS_THRU_END_OF(year - 1)
71 - LEAPS_THRU_END_OF(1970 - 1);
72 if (days < 0) {
^^^^^^^^^
73 year -= 1;
74 days += 365 + is_leap_year(year);
75 }
regards,
dan carpenter
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2016-01-05 9:57 [rtc-linux] re: rtc: fix overflow and incorrect calculation in rtc_time64_to_tm Dan Carpenter
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