From bcebd81d00a062af5a4cf900b08c8ca22a26d52f Mon Sep 17 00:00:00 2001 From: Stefan Christ Date: Tue, 15 Mar 2016 14:22:26 +0100 Subject: [PATCH] rtc: m41t80: avoid out of range year values Avoid saving an out of range year value to the RTC. Reading that value from the RTC again returns a totally wrong time value. For Example $ timedatectl set-ntp no $ timedatectl set-time "1990-01-01 12:12:00" # Reboot rtc-m41t80 0-0068: setting system clock to 2090-01-01 12:12:35 UTC (3786955955) Signed-off-by: Stefan Christ Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-m41t80.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c index a82937e2f824..d107a8e72a7d 100644 --- a/drivers/rtc/rtc-m41t80.c +++ b/drivers/rtc/rtc-m41t80.c @@ -176,7 +176,13 @@ static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm) bin2bcd(tm->tm_mday) | (buf[M41T80_REG_DAY] & ~0x3f); buf[M41T80_REG_MON] = bin2bcd(tm->tm_mon + 1) | (buf[M41T80_REG_MON] & ~0x1f); + /* assume 20YY not 19YY */ + if (tm->tm_year < 100 || tm->tm_year > 199) { + dev_err(&client->dev, "Year must be between 2000 and 2099. It's %d.\n", + tm->tm_year + 1900); + return -EINVAL; + } buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year % 100); if (i2c_transfer(client->adapter, msgs, 1) != 1) {