diff options
| author | Sanman Pradhan <psanman@juniper.net> | 2026-04-17 00:59:40 +0300 |
|---|---|---|
| committer | Guenter Roeck <linux@roeck-us.net> | 2026-04-30 20:23:59 +0300 |
| commit | 2da0c1fd01dbd6b22844e8676585153dfc660cbe (patch) | |
| tree | 77d7ab6bf0d96d260c81a8ce051658675b4c8da7 | |
| parent | d6cc7c99bf1f73eda7d565d224d791d16239bb41 (diff) | |
| download | linux-2da0c1fd01dbd6b22844e8676585153dfc660cbe.tar.xz | |
hwmon: (ltc2992) Fix u32 overflow in power read path
ltc2992_get_power() computes the divisor for mul_u64_u32_div() as
r_sense_uohm * 1000. This multiplication overflows u32 when
r_sense_uohm exceeds about 4.29 ohms (4294967 micro-ohms), producing
a truncated divisor and an incorrect power reading.
Cancel the factor of 1000 from both the numerator
(VADC_UV_LSB * IADC_NANOV_LSB = 312500000) and the divisor
(r_sense_uohm * 1000), giving (VADC_UV_LSB / 1000) * IADC_NANOV_LSB
= 312500 as the numerator and plain r_sense_uohm as the divisor.
The cancellation is exact because LTC2992_VADC_UV_LSB (25000) is
divisible by 1000.
This is the read-path counterpart of the write-path fix applied in
the preceding patch.
Fixes: b0bd407e94b03 ("hwmon: (ltc2992) Add support")
Cc: stable@vger.kernel.org
Signed-off-by: Sanman Pradhan <psanman@juniper.net>
Link: https://lore.kernel.org/r/20260416215904.101969-3-sanman.pradhan@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
| -rw-r--r-- | drivers/hwmon/ltc2992.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/hwmon/ltc2992.c b/drivers/hwmon/ltc2992.c index 106973619676..2617c4538af9 100644 --- a/drivers/hwmon/ltc2992.c +++ b/drivers/hwmon/ltc2992.c @@ -637,8 +637,10 @@ static int ltc2992_get_power(struct ltc2992_state *st, u32 reg, u32 channel, lon if (reg_val < 0) return reg_val; - *val = mul_u64_u32_div(reg_val, LTC2992_VADC_UV_LSB * LTC2992_IADC_NANOV_LSB, - st->r_sense_uohm[channel] * 1000); + *val = mul_u64_u32_div(reg_val, + LTC2992_VADC_UV_LSB / 1000 * + LTC2992_IADC_NANOV_LSB, + st->r_sense_uohm[channel]); return 0; } |