diff options
| author | Sanman Pradhan <psanman@juniper.net> | 2026-04-10 00:26:19 +0000 |
|---|---|---|
| committer | Guenter Roeck <linux@roeck-us.net> | 2026-04-10 08:32:02 -0700 |
| commit | a7c0aaa50e40ffd8fd703d006d5a04b540b9ca92 (patch) | |
| tree | c3a3b5eb86eba30f3f1b056def4215e75a5fbb42 | |
| parent | 24c73e93d6a756e1b8626bb259d2e07c5b89b370 (diff) | |
hwmon: (isl28022) Fix integer overflow in power calculation on 32-bit
isl28022_read_power() computes:
*val = ((51200000L * ((long)data->gain)) /
(long)data->shunt) * (long)regval;
On 32-bit platforms, 'long' is 32 bits. With gain=8 and shunt=10000
(the default configuration):
(51200000 * 8) / 10000 = 40960
40960 * 65535 = 2,684,313,600
This exceeds LONG_MAX (2,147,483,647), resulting in signed integer
overflow.
Additionally, dividing before multiplying by regval loses precision
unnecessarily.
Use u64 arithmetic with div_u64() and multiply before dividing to
retain precision. The intermediate product cannot overflow u64
(worst case: 51200000 * 8 * 65535 = 26843136000000). Power is
inherently non-negative, so unsigned types are the natural fit.
Cap the result to LONG_MAX before returning it through the hwmon
callback.
Fixes: 39671a14df4f2 ("hwmon: (isl28022) new driver for ISL28022 power monitor")
Cc: stable@vger.kernel.org
Signed-off-by: Sanman Pradhan <psanman@juniper.net>
Link: https://lore.kernel.org/r/20260410002613.424557-1-sanman.pradhan@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
| -rw-r--r-- | drivers/hwmon/isl28022.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/hwmon/isl28022.c b/drivers/hwmon/isl28022.c index c2e559dde63f..c5a34ceedcdb 100644 --- a/drivers/hwmon/isl28022.c +++ b/drivers/hwmon/isl28022.c @@ -9,6 +9,7 @@ #include <linux/err.h> #include <linux/hwmon.h> #include <linux/i2c.h> +#include <linux/math64.h> #include <linux/module.h> #include <linux/regmap.h> @@ -185,8 +186,8 @@ static int isl28022_read_power(struct device *dev, u32 attr, long *val) ISL28022_REG_POWER, ®val); if (err < 0) return err; - *val = ((51200000L * ((long)data->gain)) / - (long)data->shunt) * (long)regval; + *val = min(div_u64(51200000ULL * data->gain * regval, + data->shunt), LONG_MAX); break; default: return -EOPNOTSUPP; |