[PATCH] hwmon: (it87) Clamp temperatures before rounding

[PATCH] hwmon: (it87) Clamp temperatures before rounding

[Zhu Jun]

TEMP_TO_REG() adds or subtracts 500 before clamping the result. Values
near LONG_MAX or LONG_MIN can overflow, causing a high temperature limit
to select the lowest register value, or vice versa.

Clamp the requested temperature to the signed 8-bit range before
rounding to whole degrees.

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/it87.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
index b8ad1ed043b3..036e0b7ce01b 100644
--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -771,8 +771,8 @@ static inline u16 FAN16_TO_REG(long rpm)
 #define FAN16_FROM_REG(val) ((val) == 0 ? -1 : (val) == 0xffff ? 0 : \
 			     1350000 / ((val) * 2))
 
-#define TEMP_TO_REG(val) (clamp_val(((val) < 0 ? (((val) - 500) / 1000) : \
-				    ((val) + 500) / 1000), -128, 127))
+#define TEMP_TO_REG(val) \
+	DIV_ROUND_CLOSEST(clamp_val((val), -128000, 127000), 1000)
 #define TEMP_FROM_REG(val) ((val) * 1000)
 
 static u8 pwm_to_reg(const struct it87_data *data, long val)

base-commit: 7475ea8b58616b33c04afb976cf0fbaad9dd63fb
-- 
2.51.0

Re: [PATCH] hwmon: (it87) Clamp temperatures before rounding

[sashiko-bot]

> TEMP_TO_REG() adds or subtracts 500 before clamping the result. Values
> near LONG_MAX or LONG_MIN can overflow, causing a high temperature limit
> to select the lowest register value, or vice versa.
> 
> Clamp the requested temperature to the signed 8-bit range before
> rounding to whole degrees.
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")

Sashiko has reviewed this patch and found no issues.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261109101743.16955-1-zhujun2@cmss.chinamobile.com?part=1

[PATCH] hwmon: (it87) Clamp temperatures before rounding

[Zhu Jun]

TEMP_TO_REG() adds or subtracts 500 before clamping the result. Values
near LONG_MAX or LONG_MIN can overflow, causing a high temperature limit
to select the lowest register value, or vice versa.

Clamp the requested temperature to the signed 8-bit range before
rounding to whole degrees.

Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2")
Signed-off-by: Zhu Jun <zhujun2@cmss.chinamobile.com>
---
 drivers/hwmon/it87.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
index b8ad1ed043b3..036e0b7ce01b 100644
--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -771,8 +771,8 @@ static inline u16 FAN16_TO_REG(long rpm)
 #define FAN16_FROM_REG(val) ((val) == 0 ? -1 : (val) == 0xffff ? 0 : \
 			     1350000 / ((val) * 2))
 
-#define TEMP_TO_REG(val) (clamp_val(((val) < 0 ? (((val) - 500) / 1000) : \
-				    ((val) + 500) / 1000), -128, 127))
+#define TEMP_TO_REG(val) \
+	DIV_ROUND_CLOSEST(clamp_val((val), -128000, 127000), 1000)
 #define TEMP_FROM_REG(val) ((val) * 1000)
 
 static u8 pwm_to_reg(const struct it87_data *data, long val)
-- 
2.51.0

Re: [PATCH] hwmon: (it87) Clamp temperatures before rounding

[sashiko-bot]

> TEMP_TO_REG() adds or subtracts 500 before clamping the result. Values
> near LONG_MAX or LONG_MIN can overflow, causing a high temperature limit
> to select the lowest register value, or vice versa.
> 
> Clamp the requested temperature to the signed 8-bit range before
> rounding to whole degrees.
> 
> Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2")
> Signed-off-by: Zhu Jun <zhujun2@cmss.chinamobile.com>

Sashiko has reviewed this patch and found no issues.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261111065252.17695-1-zhujun2@cmss.chinamobile.com?part=1