[PATCH linux dev-5.1] hwmon (occ): Fix division by zero issue

[Joel Stanley]

On Mon, 8 Jul 2019 at 15:19, Eddie James <eajames at linux.vnet.ibm.com> wrote:
>
>
> On 7/8/19 3:32 AM, Lei YU wrote:
> > The code in occ_get_powr_avg() invokes div64_u64() without checking the
> > divisor. In case the divisor is zero, kernel gets an "Division by zero
> > in kernel" error.
> >
> > Check the divisor and make it return 0 if the divisor is 0.
>
>
> Thanks!
>
> Reviewed-by: Eddie James <eajames at linux.ibm.com>

Merged into dev-5.2.

Lei, can you please submit this to upstream? Please add Eddie's r-b to
the commit message.

Cheers,

Joel

>
>
> >
> > Signed-off-by: Lei YU <mine260309 at gmail.com>
> > ---
> >   drivers/hwmon/occ/common.c | 6 ++++--
> >   1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/hwmon/occ/common.c b/drivers/hwmon/occ/common.c
> > index e9d7167..15c5d43 100644
> > --- a/drivers/hwmon/occ/common.c
> > +++ b/drivers/hwmon/occ/common.c
> > @@ -406,8 +406,10 @@ static ssize_t occ_show_power_1(struct device *dev,
> >
> >   static u64 occ_get_powr_avg(u64 *accum, u32 *samples)
> >   {
> > -     return div64_u64(get_unaligned_be64(accum) * 1000000ULL,
> > -                      get_unaligned_be32(samples));
> > +     u64 divisor = get_unaligned_be32(samples);
> > +
> > +     return (divisor == 0) ? 0 :
> > +             div64_u64(get_unaligned_be64(accum) * 1000000ULL, divisor);
> >   }
> >
> >   static ssize_t occ_show_power_2(struct device *dev,
>