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For the INA232 with a common 2mOhm shunt, power_lsb_uW becomes 40,000. When the 16-bit regval exceeds 53,687, the product exceeds INT_MAX. This overflows the 32-bit signed math, wrapping to a negative integer and reporting erroneous negative power readings to userspace. For INA2XX_POWER, the upper bound is clamped: val = clamp_val(val, 0, UINT_MAX - data->power_lsb_uW); clamp_val() implicitly casts the upper bound to a 32-bit signed long on 32-bit platforms. This results in a negative number, meaning any valid power limit is clamped to a negative value and ultimately programmed as 0. Similarly, for INA2XX_SHUNT_VOLTAGE, the initial clamp uses SHRT_MAX * shunt_div instead of division. The subsequent multiplication: val *= data->config->shunt_div; overflows LONG_MAX on 32-bit platforms for high inputs, wrapping to a negative value and also programming the hardware limit to 0. For INA2XX_BUS_VOLTAGE on parts with bus_voltage_shift > 0, the calculation (val * 1000) << shift can exceed LONG_MAX for limits over ~134V, wrapping to negative and setting the limit to 0. For INA2XX_CURRENT: On 32-bit systems, long is 32-bit signed. For configurations with small shunts, current_lsb_uA can be very large (e.g., 40,000,000). When multiplied by a large regval, the product can reach 1.3 trillion, massively exceeding LONG_MAX (2.14 billion). This will silently overflow the 32-bit signed math, wrapping to a negative value. If a large limit is provided to effectively disable the alert (e.g., INT_MAX / 1000), the intermediate value after DIV_ROUND_CLOSEST can be large (e.g., 200,000,000). When left-shifted by current_shift (e.g., 4 for INA234), it becomes 3.2 billion, exceeding LONG_MAX and wrapping to a negative number. In sy24655_average_power_read(), the accumulator quotient multiplied by power_lsb_uW can overflow the 32-bit signed math before the assignment. Have ina2xx_get_value() return a long variable to improve the supported value range on 64-bit systems and to match the type of values returned to the hwmon core. Clamp the result of 'regval * data->power_lsb_uW' to LONG_MAX to fix the INA2XX_POWER calculation overflow. Change the initial clamp for INA2XX_SHUNT_VOLTAGE to SHRT_MAX / shunt_div to fix the shunt limit overflow. For INA2XX_BUS_VOLTAGE, limit the initial clamp to 130V instead of 200V to avoid the overflow. For INA2XX_CURRENT, improve clamping to avoid the overflow. To address the INA2XX_CURRENT problem in ina226_alert_to_reg(), take current_shift into acount for the initial clamp to avoid the overflow. In sy24655_average_power_read, use a temporary 64-bit variable to store the multiplication result and clamp the result against LONG_MAX. Cc: Loic Poulain Fixes: ab7fbee452be ("hwmon: (ina2xx) Fix various overflow issues") Signed-off-by: Guenter Roeck --- v3: Fix additional problems in INA2XX_CURRENT handling (avoid possible 64-bit divide operation and overflow when using DIV_ROUND_CLOSEST) v2: Fixed several additional overflow conditions reported by Sashiko after v1 drivers/hwmon/ina2xx.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-) diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c index c4742e84b999..a6163364fcaf 100644 --- a/drivers/hwmon/ina2xx.c +++ b/drivers/hwmon/ina2xx.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -266,10 +267,11 @@ static u16 ina226_interval_to_reg(long interval) return FIELD_PREP(INA226_AVG_RD_MASK, avg_bits); } -static int ina2xx_get_value(struct ina2xx_data *data, u8 reg, - unsigned int regval) +static long ina2xx_get_value(struct ina2xx_data *data, u8 reg, + unsigned int regval) { - int val; + s64 val64; + long val; switch (reg) { case INA2XX_SHUNT_VOLTAGE: @@ -283,12 +285,13 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 reg, val = DIV_ROUND_CLOSEST(val, 1000); break; case INA2XX_POWER: - val = regval * data->power_lsb_uW; + val = clamp_val((u64)regval * data->power_lsb_uW, 0, LONG_MAX); break; case INA2XX_CURRENT: /* signed register, result in mA */ - val = ((s16)regval >> data->config->current_shift) * + val64 = (s64)((s16)regval >> data->config->current_shift) * data->current_lsb_uA; + val = clamp_val(val64, LONG_MIN, LONG_MAX); val = DIV_ROUND_CLOSEST(val, 1000); break; case INA2XX_CALIBRATION: @@ -378,23 +381,27 @@ static int ina2xx_read_init(struct device *dev, int reg, long *val) */ static u16 ina226_alert_to_reg(struct ina2xx_data *data, int reg, long val) { + long limit; + switch (reg) { case INA2XX_SHUNT_VOLTAGE: - val = clamp_val(val, 0, SHRT_MAX * data->config->shunt_div); + val = clamp_val(val, 0, DIV_ROUND_CLOSEST(SHRT_MAX, data->config->shunt_div)); val *= data->config->shunt_div; val <<= data->config->shunt_voltage_shift; return clamp_val(val, 0, SHRT_MAX); case INA2XX_BUS_VOLTAGE: - val = clamp_val(val, 0, 200000); + val = clamp_val(val, 0, 130000); val = (val * 1000) << data->config->bus_voltage_shift; val = DIV_ROUND_CLOSEST(val, data->config->bus_voltage_lsb); return clamp_val(val, 0, USHRT_MAX); case INA2XX_POWER: - val = clamp_val(val, 0, UINT_MAX - data->power_lsb_uW); + val = clamp_val(val, 0, LONG_MAX - data->power_lsb_uW); val = DIV_ROUND_CLOSEST(val, data->power_lsb_uW); return clamp_val(val, 0, USHRT_MAX); case INA2XX_CURRENT: - val = clamp_val(val, INT_MIN / 1000, INT_MAX / 1000); + limit = ((INT_MAX - data->current_lsb_uA) / 1000) >> + data->config->current_shift; + val = clamp_val(val, -limit, limit); /* signed register, result in mA */ val = DIV_ROUND_CLOSEST(val * 1000, data->current_lsb_uA); val <<= data->config->current_shift; @@ -537,6 +544,7 @@ static int sy24655_average_power_read(struct ina2xx_data *data, u8 reg, long *va u8 template[6]; int ret; long accumulator_24, sample_count; + u64 val64; /* 48-bit register read */ ret = i2c_smbus_read_i2c_block_data(data->client, reg, 6, template); @@ -555,7 +563,8 @@ static int sy24655_average_power_read(struct ina2xx_data *data, u8 reg, long *va return 0; } - *val = DIV_ROUND_CLOSEST(accumulator_24, sample_count) * data->power_lsb_uW; + val64 = (u64)DIV_ROUND_CLOSEST(accumulator_24, sample_count) * data->power_lsb_uW; + *val = clamp_val(val64, 0, LONG_MAX); return 0; } -- 2.45.2