Re: [lm-sensors] [PATCH] hwmon: (adm1031) Fix writes to limit registers

[Guenter Roeck <linux@roeck-us.net>]

Hi Jean,

On 07/07/2014 12:10 AM, Jean Delvare wrote:
> Hi Guenter,
>
> On Thu,  3 Jul 2014 13:56:59 -0700, Guenter Roeck wrote:
>> Upper limit for write operations to temperature limit registers
>> was clamped to a fractional value. However, limit registers do
>> not support fractional values. As a result, upper limits of 127.5
>> degrees C or higher resulted in a rounded limit of 128 degrees C.
>> Since limit registers are signed, this was stored as -128 degrees C.
>> Clamp limits to (-55, +127) degrees C to solve the problem.
>
> Good catch, sorry for missing this bug during my original review.
>
Easy to miss without explicit module test, really. I bet we have a
lot of similar problems in other drivers ;-).

>> Value on writes to auto_temp[12]_min and auto_temp[12]_max were not
>> clamped at all, but masked. As a result, out-of-range writes resulted
>> in a more or less arbitrary limit. Clamp those attributes to (0, 127)
>> degrees C for more predictable results.
>
> Ditto.
>
>> Cc: Axel Lin <axel.lin@ingics.com>
>> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
>> ---
>>   drivers/hwmon/adm1031.c | 8 +++++---
>>   1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/hwmon/adm1031.c b/drivers/hwmon/adm1031.c
>> index a8a540c..9eaa235 100644
>> --- a/drivers/hwmon/adm1031.c
>> +++ b/drivers/hwmon/adm1031.c
>> @@ -366,6 +366,7 @@ set_auto_temp_min(struct device *dev, struct device_attribute *attr,
>>   		return ret;
>>
>>   	mutex_lock(&data->update_lock);
>> +	val = clamp_val(val, 0, 127000);
>
> For consistency and performance, please clamp the value before locking
> the mutex.
>
>>   	data->auto_temp[nr] = AUTO_TEMP_MIN_TO_REG(val, data->auto_temp[nr]);
>>   	adm1031_write_value(client, ADM1031_REG_AUTO_TEMP(nr),
>>   			    data->auto_temp[nr]);
>> @@ -395,6 +396,7 @@ set_auto_temp_max(struct device *dev, struct device_attribute *attr,
>>   		return ret;
>>
>>   	mutex_lock(&data->update_lock);
>> +	val = clamp_val(val, 0, 127000);
>
> Same here.
>
Ok, done.

>>   	data->temp_max[nr] = AUTO_TEMP_MAX_TO_REG(val, data->auto_temp[nr],
>>   						  data->pwm[nr]);
>>   	adm1031_write_value(client, ADM1031_REG_AUTO_TEMP(nr),
>> @@ -696,7 +698,7 @@ static ssize_t set_temp_min(struct device *dev, struct device_attribute *attr,
>>   	if (ret)
>>   		return ret;
>>
>> -	val = clamp_val(val, -55000, nr = 0 ? 127750 : 127875);
>> +	val = clamp_val(val, -55000, 127000);
>>   	mutex_lock(&data->update_lock);
>>   	data->temp_min[nr] = TEMP_TO_REG(val);
>>   	adm1031_write_value(client, ADM1031_REG_TEMP_MIN(nr),
>> @@ -717,7 +719,7 @@ static ssize_t set_temp_max(struct device *dev, struct device_attribute *attr,
>>   	if (ret)
>>   		return ret;
>>
>> -	val = clamp_val(val, -55000, nr = 0 ? 127750 : 127875);
>> +	val = clamp_val(val, -55000, 127000);
>>   	mutex_lock(&data->update_lock);
>>   	data->temp_max[nr] = TEMP_TO_REG(val);
>>   	adm1031_write_value(client, ADM1031_REG_TEMP_MAX(nr),
>> @@ -738,7 +740,7 @@ static ssize_t set_temp_crit(struct device *dev, struct device_attribute *attr,
>>   	if (ret)
>>   		return ret;
>>
>> -	val = clamp_val(val, -55000, nr = 0 ? 127750 : 127875);
>> +	val = clamp_val(val, -55000, 127000);
>>   	mutex_lock(&data->update_lock);
>>   	data->temp_crit[nr] = TEMP_TO_REG(val);
>>   	adm1031_write_value(client, ADM1031_REG_TEMP_CRIT(nr),
>
> Reviewed-by: Jean Delvare <jdelvare@suse.de>
>
Thanks!

Guenter


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