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Commit c0d04e91 authored by Guenter Roeck's avatar Guenter Roeck
Browse files

hwmon: (nct7802) Fix overflows seen when writing into limit attributes 



Fix overflows seen when writing voltage and temperature limit attributes.

The value passed to DIV_ROUND_CLOSEST() needs to be clamped, and the
value parameter passed to nct7802_write_fan_min() is an unsigned long.

Also, writing values larger than 2700000 into a fan limit attribute results
in writing 0 into the chip's limit registers. The exact behavior when
writing this value is unspecified. For consistency, report a limit of
1350000 if the chip register reads 0. This may be wrong, and the chip
behavior should be verified with the actual chip, but it is better than
reporting a value of 0 (which, when written, results in writing a value
of 0x1fff into the chip register).

Fixes: 3434f378 ("hwmon: Driver for Nuvoton NCT7802Y")
Reviewed-by: default avatarJean Delvare <jdelvare@suse.de>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 64bd708a

drivers/hwmon/nct7802.c

+5 −3
Original line number Diff line number Diff line
@@ -259,13 +259,15 @@ static int nct7802_read_fan_min(struct nct7802_data *data, u8 reg_fan_low, 
		ret = 0;

	else if (ret)

		ret = DIV_ROUND_CLOSEST(1350000U, ret);

	else

		ret = 1350000U;

abort:

	mutex_unlock(&data->access_lock);

	return ret;

}



static int nct7802_write_fan_min(struct nct7802_data *data, u8 reg_fan_low,

				 u8 reg_fan_high, unsigned int limit)

				 u8 reg_fan_high, unsigned long limit)

{

	int err;
@@ -326,8 +328,8 @@ static int nct7802_write_voltage(struct nct7802_data *data, int nr, int index, 
	int shift = 8 - REG_VOLTAGE_LIMIT_MSB_SHIFT[index - 1][nr];

	int err;



	voltage = clamp_val(voltage, 0, 0x3ff * nct7802_vmul[nr]);

	voltage = DIV_ROUND_CLOSEST(voltage, nct7802_vmul[nr]);

	voltage = clamp_val(voltage, 0, 0x3ff);



	mutex_lock(&data->access_lock);

	err = regmap_write(data->regmap,
@@ -402,7 +404,7 @@ static ssize_t store_temp(struct device *dev, struct device_attribute *attr, 
	if (err < 0)

		return err;



	val = clamp_val(DIV_ROUND_CLOSEST(val, 1000), -128, 127);

	val = DIV_ROUND_CLOSEST(clamp_val(val, -128000, 127000), 1000);



	err = regmap_write(data->regmap, nr, val & 0xff);

	return err ? : count;