According to ACPI specification, the century field data
should be ranged 0-63. so if it's over this range, it could
cause system RTC settings error including alarmwakeup settings.
So it's required to have this boundary for safe RTC init settings.
Signed-off-by: Andrew Kim <andrew....@intel.com>
---
arch/x86/kernel/rtc.c | 7 +++++--
drivers/rtc/rtc-mc146818-lib.c | 7 +++++--
include/linux/mc146818rtc.h | 2 ++
3 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
index 79c6311c..feac180 100644
--- a/arch/x86/kernel/rtc.c
+++ b/arch/x86/kernel/rtc.c
@@ -84,8 +84,11 @@ void mach_get_cmos_time(struct timespec *now)
#ifdef CONFIG_ACPI
if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
- acpi_gbl_FADT.century)
- century = CMOS_READ(acpi_gbl_FADT.century);
+ acpi_gbl_FADT.century) {
+ if ((century = CMOS_READ(acpi_gbl_FADT.century)) >
+ RTC_CENTURY_LIMIT)
+ century = 0;
+ }
#endif
status = CMOS_READ(RTC_CONTROL);
diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c
index 2f1772a..1d83c2c 100644
--- a/drivers/rtc/rtc-mc146818-lib.c
+++ b/drivers/rtc/rtc-mc146818-lib.c
@@ -61,8 +61,11 @@ unsigned int mc146818_get_time(struct rtc_time *time)
#endif
#ifdef CONFIG_ACPI
if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
- acpi_gbl_FADT.century)
- century = CMOS_READ(acpi_gbl_FADT.century);
+ acpi_gbl_FADT.century) {
+ if ((century = CMOS_READ(acpi_gbl_FADT.century)) >
+ RTC_CENTURY_LIMIT)
+ century = 0;
+ }
#endif
ctrl = CMOS_READ(RTC_CONTROL);
spin_unlock_irqrestore(&rtc_lock, flags);
diff --git a/include/linux/mc146818rtc.h b/include/linux/mc146818rtc.h
index a585b4b..199065a 100644
--- a/include/linux/mc146818rtc.h
+++ b/include/linux/mc146818rtc.h
@@ -122,6 +122,8 @@ struct cmos_rtc_board_info {
#define RTC_IO_EXTENT_USED RTC_IO_EXTENT
#endif /* ARCH_RTC_LOCATION */
+#define RTC_CENTURY_LIMIT 0x3F
+
unsigned int mc146818_get_time(struct rtc_time *time);
int mc146818_set_time(struct rtc_time *time);
--
1.9.1
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