From: Nikita Zhandarovich n.zhandarovich@fintech.ru
[ Upstream commit 0babf89c9cca7e074d6e59893e462e4886f481cc ]
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@fintech.ru Link: https://lore.kernel.org/r/20230510143537.145060-1-n.zhandarovich@fintech.ru Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Sasha Levin sashal@kernel.org --- 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 70121482a6173..27207ec6f7feb 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);