From: Sanman Pradhan Date: Fri, 10 Apr 2026 00:26:19 +0000 (+0000) Subject: hwmon: (isl28022) Fix integer overflow in power calculation on 32-bit X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a7c0aaa50e40ffd8fd703d006d5a04b540b9ca92;p=thirdparty%2Fkernel%2Flinux.git 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 Link: https://lore.kernel.org/r/20260410002613.424557-1-sanman.pradhan@hpe.com Signed-off-by: Guenter Roeck --- diff --git a/drivers/hwmon/isl28022.c b/drivers/hwmon/isl28022.c index c2e559dde63f6..c5a34ceedcdb2 100644 --- a/drivers/hwmon/isl28022.c +++ b/drivers/hwmon/isl28022.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include @@ -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;