Re: [BUG] power: supply: 88pm860x_battery: possible uninitialized-variable access in measure_vbatt()

Thanks for your feedback, and any further feedback about this problem 
would be appreciated.

Best wishes,
Tuo Li

On 2021/8/6 1:49, Sebastian Reichel wrote:

[adding Jett Zhou to Cc who introduced the driver]

Hi,

On Wed, Jul 28, 2021 at 06:24:12PM +0800, Li Tuo wrote:

quoted

Our static analysis tool finds a possible uninitialized-variable access in
the 88pm860x_battery driver in Linux 5.14.0-rc3:

In calc_soc():
369:    int ocv;
376:    switch (state) {
380:    case OCV_MODE_SLEEP:
381:        ret = measure_vbatt(info, OCV_MODE_SLEEP, &ocv);

In measure_vbatt(struct pm860x_battery_info *info, int state, int *data)
176:    switch (state) {
184:    case OCV_MODE_SLEEP:
201:        *data = ((*data & 0xff) * 27 * 25) >> 9;

If the variable state is OCV_MODE_SLEEP, the function measure_vbatt() is
called with the argument &ocv, and the corresponding parameter is data.
Thus *data is uninitialized but it is used at line 201.

I am not quite sure whether this possible uninitialized-variable access is
real and how to fix it if it is real.
Any feedback would be appreciated, thanks!

Reported-by: TOTE Robot <redacted>

I suppose the code is suppose to look like this:

201:        *data = ((ret & 0xff) * 27 * 25) >> 9;

Considering quite some code is spent before to setup ret, which is
never used. I don't have the device (nor datasheets) though. Considering
the driver has only seen trivial cleanups over the last 9 years, maybe
it can just be removed?

-- Sebastian