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rtc: fix overflow in mktimegm 

When setting a date in 1980, Linux is actually disregarding the century
byte and setting the year to 2080.  This causes a year-2038 overflow
in mktimegm.  Fix this by doing the days-to-seconds computation in
64-bit math.

Reported-by: Lucas Meneghel Rodrigues <lookkas@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Paolo Bonzini 2012-10-01 14:22:06 +02:00 committed by Anthony Liguori
parent e0fea6b1e4
commit b6db4aca20
2 changed files with 46 additions and 1 deletions
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2
cutils.c
View File

@ -115,7 +115,7 @@ time_t mktimegm(struct tm *tm)
m += 12;
y--;
}
t = 86400 * (d + (153 * m - 457) / 5 + 365 * y + y / 4 - y / 100 +
t = 86400ULL * (d + (153 * m - 457) / 5 + 365 * y + y / 4 - y / 100 +
y / 400 - 719469);
t += 3600 * tm->tm_hour + 60 * tm->tm_min + tm->tm_sec;
return t;

45
tests/rtc-test.c
View File

@ -179,6 +179,50 @@ static void check_time(int wiggle)
static int wiggle = 2;
static void set_year(void)
{
/* Set BCD mode */
cmos_write(RTC_REG_B, cmos_read(RTC_REG_B) & ~REG_B_DM);
cmos_write(RTC_REG_A, 0x76);
cmos_write(RTC_YEAR, 0x11);
cmos_write(RTC_MONTH, 0x02);
cmos_write(RTC_DAY_OF_MONTH, 0x02);
cmos_write(RTC_HOURS, 0x02);
cmos_write(RTC_MINUTES, 0x04);
cmos_write(RTC_SECONDS, 0x58);
cmos_write(RTC_REG_A, 0x26);
g_assert_cmpint(cmos_read(RTC_HOURS), ==, 0x02);
g_assert_cmpint(cmos_read(RTC_MINUTES), ==, 0x04);
g_assert_cmpint(cmos_read(RTC_SECONDS), >=, 0x58);
g_assert_cmpint(cmos_read(RTC_DAY_OF_MONTH), ==, 0x02);
g_assert_cmpint(cmos_read(RTC_MONTH), ==, 0x02);
g_assert_cmpint(cmos_read(RTC_YEAR), ==, 0x11);
/* Set a date in 2080 to ensure there is no year-2038 overflow. */
cmos_write(RTC_REG_A, 0x76);
cmos_write(RTC_YEAR, 0x80);
cmos_write(RTC_REG_A, 0x26);
g_assert_cmpint(cmos_read(RTC_HOURS), ==, 0x02);
g_assert_cmpint(cmos_read(RTC_MINUTES), ==, 0x04);
g_assert_cmpint(cmos_read(RTC_SECONDS), >=, 0x58);
g_assert_cmpint(cmos_read(RTC_DAY_OF_MONTH), ==, 0x02);
g_assert_cmpint(cmos_read(RTC_MONTH), ==, 0x02);
g_assert_cmpint(cmos_read(RTC_YEAR), ==, 0x80);
cmos_write(RTC_REG_A, 0x76);
cmos_write(RTC_YEAR, 0x11);
cmos_write(RTC_REG_A, 0x26);
g_assert_cmpint(cmos_read(RTC_HOURS), ==, 0x02);
g_assert_cmpint(cmos_read(RTC_MINUTES), ==, 0x04);
g_assert_cmpint(cmos_read(RTC_SECONDS), >=, 0x58);
g_assert_cmpint(cmos_read(RTC_DAY_OF_MONTH), ==, 0x02);
g_assert_cmpint(cmos_read(RTC_MONTH), ==, 0x02);
g_assert_cmpint(cmos_read(RTC_YEAR), ==, 0x11);
}
static void bcd_check_time(void)
{
/* Set BCD mode */
@ -269,6 +313,7 @@ int main(int argc, char **argv)
qtest_add_func("/rtc/bcd/check-time", bcd_check_time);
qtest_add_func("/rtc/dec/check-time", dec_check_time);
qtest_add_func("/rtc/alarm-time", alarm_time);
qtest_add_func("/rtc/set-year", set_year);
qtest_add_func("/rtc/fuzz-registers", fuzz_registers);
ret = g_test_run();