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

[Tuo Li]

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:
> > 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 <oslab@xxxxxxxxxxxxxxx>
> 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