[PATCH] rtc: tps65910: add bounds checking

[SZ Lin (æäæ)]

Since tm->tm_year is the offset relative to 1900, it needs to check for
positive value to avoid overflow in YEARS_REG register.

The system will hang at the following stage on the next boot when overflow
has occurred.

[    2.221192] systemd[1]: Time has been changed

This patch fixes the above hanging issue by adding bounds checking.

Signed-off-by: Taiyi Wu <taiyity.wu@xxxxxxxx>
Signed-off-by: SZ Lin (æäæ) <sz.lin@xxxxxxxx>
---
 drivers/rtc/rtc-tps65910.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/rtc/rtc-tps65910.c b/drivers/rtc/rtc-tps65910.c
index d0244d7979fc..6be9f7bb0f1b 100644
--- a/drivers/rtc/rtc-tps65910.c
+++ b/drivers/rtc/rtc-tps65910.c
@@ -105,6 +105,12 @@ static int tps65910_rtc_set_time(struct device *dev, struct rtc_time *tm)
 	struct tps65910 *tps = dev_get_drvdata(dev->parent);
 	int ret;
 
+	if ((tm->tm_year - 100) < 0) {
+		dev_err(dev, "the requested year %d is unsupported\n",
+			1900 + tm->tm_year);
+		return -EINVAL;
+	}
+
 	rtc_data[0] = bin2bcd(tm->tm_sec);
 	rtc_data[1] = bin2bcd(tm->tm_min);
 	rtc_data[2] = bin2bcd(tm->tm_hour);
-- 
2.15.1