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hwmon: (f71882fg) prevent possible division by zero

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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: df9ec2dae0 ("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>
This commit is contained in:
Nikita Zhandarovich 2023-05-10 07:35:37 -07:00 committed by Guenter Roeck
parent f1fcbaa18b
commit 0babf89c9c
1 changed files with 5 additions and 2 deletions
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7
drivers/hwmon/f71882fg.c
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@ -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);