Re: [PATCH] kselftest: vDSO: Fix accumulation of uninitialized ret when CLOCK_REALTIME is undefined

[Colin King (gmail)]

On 18/04/2023 11:10, Vincenzo Frascino wrote:
> Hi Colin,
>
> On 4/17/23 11:47, Colin Ian King wrote:
> > In the unlikely case that CLOCK_REALTIME is not defined, variable ret is
> > not initialized and further accumulation of return values to ret can leave
> > ret in an undefined state. Fix this by initialized ret to zero and changing
> > the assignment of ret to an accumulation for the CLOCK_REALTIME case.
>
> I was wondering how did you find this.

I used cppcheck --force --enable=all, this examines the #if defined() paths.

> Apart that:
>
> Reviewed-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
>
> > Fixes: 03f55c7952c9 ("kselftest: Extend vDSO selftest to clock_getres")
> > Signed-off-by: Colin Ian King <colin.i.king@xxxxxxxxx>
> > ---
> >   tools/testing/selftests/vDSO/vdso_test_clock_getres.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/testing/selftests/vDSO/vdso_test_clock_getres.c b/tools/testing/selftests/vDSO/vdso_test_clock_getres.c
> > index 15dcee16ff72..38d46a8bf7cb 100644
> > --- a/tools/testing/selftests/vDSO/vdso_test_clock_getres.c
> > +++ b/tools/testing/selftests/vDSO/vdso_test_clock_getres.c
> > @@ -84,12 +84,12 @@ static inline int vdso_test_clock(unsigned int clock_id)
> >   
> >   int main(int argc, char **argv)
> >   {
> > -	int ret;
> > +	int ret = 0;
> >   
> >   #if _POSIX_TIMERS > 0
> >   
> >   #ifdef CLOCK_REALTIME
> > -	ret = vdso_test_clock(CLOCK_REALTIME);
> > +	ret += vdso_test_clock(CLOCK_REALTIME);
> >   #endif
> >   
> >   #ifdef CLOCK_BOOTTIME