hwmon: (lm77) Prevent overflow problem when writing large limits (99765db2) · Commits · 戴 / test

On platforms with sizeof(int) < sizeof(long), writing a temperature limit larger than MAXINT will result in unpredictable limit values written to the chip. Clamp the input values to the supported limits first to fix the problem. For set_temp_hyst: As Guenter pointed out that the temperature is read as unsigned and stored in an unsigned long. This is wrong; nothing in the datasheet suggests that the value (the absolute temperature) must be positive. So change it to signed. Signed-off-by:

Axel Lin <axel.lin@ingics.com> Signed-off-by:

Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/lm77.c

+6 −5

Original line number	Diff line number	Diff line
		@@ -80,8 +80,7 @@ struct lm77_data {
		*/
		static inline s16 LM77_TEMP_TO_REG(int temp)
		{
		int ntemp = clamp_val(temp, LM77_TEMP_MIN, LM77_TEMP_MAX);
		return (ntemp / 500) * 8;
		return (temp / 500) * 8;
		}

		static inline int LM77_TEMP_FROM_REG(s16 reg)
		@@ -175,6 +174,7 @@ static ssize_t set_temp(struct device dev, struct device_attribute devattr,
		if (err)
		return err;

		val = clamp_val(val, LM77_TEMP_MIN, LM77_TEMP_MAX);
		mutex_lock(&data->update_lock);
		data->temp[nr] = val;
		lm77_write_value(client, temp_regs[nr], LM77_TEMP_TO_REG(val));
		@@ -192,15 +192,16 @@ static ssize_t set_temp_hyst(struct device *dev,
		{
		struct lm77_data *data = dev_get_drvdata(dev);
		struct i2c_client *client = data->client;
		unsigned long val;
		long val;
		int err;

		err = kstrtoul(buf, 10, &val);
		err = kstrtol(buf, 10, &val);
		if (err)
		return err;

		mutex_lock(&data->update_lock);
		data->temp[t_hyst] = data->temp[t_crit] - val;
		val = clamp_val(data->temp[t_crit] - val, LM77_TEMP_MIN, LM77_TEMP_MAX);
		data->temp[t_hyst] = val;
		lm77_write_value(client, LM77_REG_TEMP_HYST,
		LM77_TEMP_TO_REG(data->temp[t_hyst]));
		mutex_unlock(&data->update_lock);

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