hwmon: (adt7470) Prevent divide by zero in adt7470_fan_write()

BugLink: https://bugs.launchpad.net/bugs/1959879
[ Upstream commit c1ec0cabc36718efc7fe8b4157d41b82d08ec1d2 ]

The "val" variable is controlled by the user and comes from
hwmon_attr_store().  The FAN_RPM_TO_PERIOD() macro divides by "val"
so a zero will crash the system.  Check for that and return -EINVAL.
Negatives are also invalid so return -EINVAL for those too.

Fixes: fc958a61ff6d ("hwmon: (adt7470) Convert to devm_hwmon_device_register_with_info API")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

diff --git a/drivers/hwmon/adt7470.c b/drivers/hwmon/adt7470.c
index d519aca4a9d645a732e1f39f70fc9d9c07c6aafc..fb6d14d213a18c8595e8111f6c0c72890e1c0d61 100644 (file)
--- a/drivers/hwmon/adt7470.c
+++ b/drivers/hwmon/adt7470.c
@@ -662,6 +662,9 @@ static int adt7470_fan_write(struct device *dev, u32 attr, int channel, long val
        struct adt7470_data *data = dev_get_drvdata(dev);
        int err;
 
+       if (val <= 0)
+               return -EINVAL;
+
        val = FAN_RPM_TO_PERIOD(val);
        val = clamp_val(val, 1, 65534);