Re: [bug report] hwmon: Add "label" attribute

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

On 1/27/22 01:47, Paul Cercueil wrote:
> Hi,
> 
> Le jeu., janv. 27 2022 at 11:52:45 +0300, Dan Carpenter <dan.carpenter@oracle.com> a écrit :
>> Hello Paul Cercueil,
>>
>> This is a semi-automatic email about new static checker warnings.
>>
>> The patch 073c3ea6c530: "hwmon: Add "label" attribute" from Jan 10,
>> 2022, leads to the following Smatch complaint:
>>
>>     drivers/hwmon/hwmon.c:825 __hwmon_device_register()
>>     warn: variable dereferenced before check 'dev' (see line 810)
>>
>> drivers/hwmon/hwmon.c
>>    809
>>    810        if (device_property_present(dev, "label")) {
>>                                             ^^^
>> The patch adds a new unchecked dereference
> 
> I will send a patch to address that.
> 
> I'm surprised that this function can be called with dev == NULL in the first place, though.
> 

Originally it was needed for the thermal subsystem, which did not provide a parent
device. By the time that was reworked, it was (mis-)used by the Loongson-3 hwmon
driver (which was never reviewed by a hwmon maintainer and does pretty much
everything wrong).

Guenter