On Sun, 2016-08-21 at 23:20 +0200, Heinrich Schuchardt wrote:
> On 08/21/2016 11:06 PM, Joe Perches wrote:
> > On Sun, 2016-08-21 at 22:52 +0200, Heinrich Schuchardt wrote:
> > >
> > > It does not make sense to check if table is NULL
> > > and afterwards to dereference it without
> > > considering the result.
> > This makes no sense.
> > > The inconsistency was indicated by cppcheck.
> > Perhaps this is a defect in cppcheck?
> > > An actual NULL pointer dereference was not observed.
> > []
> > > diff --git a/drivers/gpu/drm/radeon/si_dpm.c b/drivers/gpu/drm/radeon/si_dpm.c
> > []
> > > @@ -2962,7 +2962,7 @@ static int si_get_vce_clock_voltage(struct radeon_device *rdev,
> > > &rdev->pm.dpm.dyn_state.vce_clock_voltage_dependency_table;
> > >
> > > if (((evclk == 0) && (ecclk == 0)) ||
> > > - (table && (table->count == 0))) {
> > Here table is only dereferenced if table is non-null
> > >
> > > + table == NULL || table->count == 0) {
> > > *voltage = 0;
> > > return 0;
> > > }
> > Perhaps the unnecessary parentheses can be reduce though.
> >
> > if ((evclk == 0 && ecclk == 0) || (table && table->count == 0)) {
> >
> The possible NULL pointer dereference would occur here:
>
> 2970 for (i = 0; i < table->count; i++) {
This still doesn't make any sense as table is known non-null
at line 2961
struct radeon_vce_clock_voltage_dependency_table *table =
&rdev->pm.dpm.dyn_state.vce_clock_voltage_dependency_table;
So I now suggest simply removing the test for table.
Perhaps cppcheck can be improved to know about known non-null pointers.
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