diff mbox

[1/1] rtc: add century field data boundary

Message ID 1475604344-51781-1-git-send-email-andrew.kim@intel.com
State Changes Requested
Headers show

Commit Message

Andrew Kim Oct. 4, 2016, 6:05 p.m. UTC 
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.kim@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 mbox

Patch

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);