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

[Eddie James]

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>


>
> 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,