From: Sanman Pradhan Date: Thu, 16 Apr 2026 21:59:40 +0000 (+0000) Subject: hwmon: (ltc2992) Fix u32 overflow in power read path X-Git-Tag: v7.1-rc3~7^2~7 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2da0c1fd01dbd6b22844e8676585153dfc660cbe;p=thirdparty%2Fkernel%2Flinux.git 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 Link: https://lore.kernel.org/r/20260416215904.101969-3-sanman.pradhan@hpe.com Signed-off-by: Guenter Roeck --- 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; }