On Wed, May 10, 2023 at 07:35:37AM -0700, Nikita Zhandarovich wrote:
> In the unlikely event that something goes wrong with the device and
> its registers, the fan_from_reg() function may return 0. This value
> will cause a division-by-zero error in the show_pwm() function.
>
> To prevent this, test the value of
> fan_from_reg(data->fan_full_speed[nr]) against 0 before performing
> the division. If the division-by-zero error is avoided, assign 0 to
> the val variable.
>
> Found by Linux Verification Center (linuxtesting.org) with static
> analysis tool SVACE.
>
> Fixes: df9ec2dae094 ("hwmon: (f71882fg) Reorder symbols to get rid of a few forward declarations")
> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@xxxxxxxxxx>
Applied.
Thanks,
Guenter
> ---
> drivers/hwmon/f71882fg.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hwmon/f71882fg.c b/drivers/hwmon/f71882fg.c
> index 70121482a617..27207ec6f7fe 100644
> --- a/drivers/hwmon/f71882fg.c
> +++ b/drivers/hwmon/f71882fg.c
> @@ -1096,8 +1096,11 @@ static ssize_t show_pwm(struct device *dev,
> val = data->pwm[nr];
> else {
> /* RPM mode */
> - val = 255 * fan_from_reg(data->fan_target[nr])
> - / fan_from_reg(data->fan_full_speed[nr]);
> + if (fan_from_reg(data->fan_full_speed[nr]))
> + val = 255 * fan_from_reg(data->fan_target[nr])
> + / fan_from_reg(data->fan_full_speed[nr]);
> + else
> + val = 0;
> }
> mutex_unlock(&data->update_lock);
> return sprintf(buf, "%d\n", val);
