[PATCH] hwmon: (lm80) Clamp voltage limits before rounding

[Zhu Jun]

IN_TO_REG() adds 5 to the signed sysfs value before clamping the
register result. A voltage limit close to LONG_MAX can overflow and be
programmed as zero instead of the maximum.

Clamp to the 0..2550 mV register range before rounding to 10 mV units.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
---
Validation: x86-64 and i386 driver objects built with W=1.
Source-extracted boundary tests passed on both word sizes;
the corresponding test fails on the base revision. I/O is mocked.
No physical sensor or booted-kernel testing was available.
OpenAI Codex assisted analysis, code, tests and changelog drafting.
Please review and add your own Signed-off-by before submitting.

 drivers/hwmon/lm80.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwmon/lm80.c b/drivers/hwmon/lm80.c
index 079f79d9b02f..9864df05d24c 100644
--- a/drivers/hwmon/lm80.c
+++ b/drivers/hwmon/lm80.c
@@ -59,7 +59,7 @@ static const unsigned short normal_i2c[] = { 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d,
  * Fixing this is just not worth it.
  */
 
-#define IN_TO_REG(val)		(clamp_val(((val) + 5) / 10, 0, 255))
+#define IN_TO_REG(val)		((clamp_val((val), 0, 2550) + 5) / 10)
 #define IN_FROM_REG(val)	((val) * 10)
 
 static inline unsigned char FAN_TO_REG(unsigned rpm, unsigned div)

base-commit: 7475ea8b58616b33c04afb976cf0fbaad9dd63fb
-- 
2.51.0