[PATCH] hwmon: (nct6775) Clamp fan control times before rounding

[Zhu Jun]

store_fan_time() accepts an unsigned long, but step_time_to_reg()
narrows it to unsigned int and adds the rounding adjustment before
clamping. For example, 4294967295 ms wraps and selects register 1
instead of 255 in either mode.

Preserve the input width and clamp to the maximum duration for the
selected mode before rounding.

Signed-off-by: Zhu Jun <zhujun2@xxxxxxxxxxxxxxxxxxxx>
---
 drivers/hwmon/nct6775-core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/nct6775-core.c b/drivers/hwmon/nct6775-core.c
index 6e97e4f08b90..76b2c9551a1c 100644
--- a/drivers/hwmon/nct6775-core.c
+++ b/drivers/hwmon/nct6775-core.c
@@ -949,8 +949,9 @@ static unsigned int step_time_from_reg(u8 reg, u8 mode)
 	return mode ? 400 * reg : 100 * reg;
 }
 
-static u8 step_time_to_reg(unsigned int msec, u8 mode)
+static u8 step_time_to_reg(unsigned long msec, u8 mode)
 {
+	msec = min(msec, 255UL * (mode ? 400 : 100));
 	return clamp_val((mode ? (msec + 200) / 400 :
 					(msec + 50) / 100), 1, 255);
 }
-- 
2.51.0