[PATCH] hwmon: (nct6775) Clamp voltage limits before narrowing and scaling

[Zhu Jun]

store_in_reg() parses an unsigned long, but in_to_reg() takes a u32 and
multiplies it by 100 before clamping. Large limits can therefore wrap to
a low register value. For example, 4294967296 mV becomes zero on a
64-bit system.

Keep the input as an unsigned long and bound it to the register range
before scaling.

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..b7c1e8ceaac9 100644
--- a/drivers/hwmon/nct6775-core.c
+++ b/drivers/hwmon/nct6775-core.c
@@ -1039,8 +1039,9 @@ static inline long in_from_reg(u8 reg, u8 nr, const u16 *scales)
 	return DIV_ROUND_CLOSEST(reg * scales[nr], 100);
 }
 
-static inline u8 in_to_reg(u32 val, u8 nr, const u16 *scales)
+static inline u8 in_to_reg(unsigned long val, u8 nr, const u16 *scales)
 {
+	val = min(val, 255UL * scales[nr] / 100);
 	return clamp_val(DIV_ROUND_CLOSEST(val * 100, scales[nr]), 0, 255);
 }
 
-- 
2.51.0