From 46c28bbbb150b80827e4bcbea231560af9d16854 Mon Sep 17 00:00:00 2001 From: Denis Sergeev Date: Tue, 9 Dec 2025 09:37:06 +0300 Subject: [PATCH] hwmon: (dell-smm) Limit fan multiplier to avoid overflow The fan nominal speed returned by SMM is limited to 16 bits, but the driver allows the fan multiplier to be set via a module parameter. Clamp the computed fan multiplier so that fan_nominal_speed * i8k_fan_mult always fits into a signed 32-bit integer and refuse to initialize the driver if the value is too large. Found by Linux Verification Center (linuxtesting.org) with SVACE. Fixes: 20bdeebc88269 ("hwmon: (dell-smm) Introduce helper function for data init") Signed-off-by: Denis Sergeev Link: https://lore.kernel.org/r/20251209063706.49008-1-denserg.edu@gmail.com Signed-off-by: Guenter Roeck --- drivers/hwmon/dell-smm-hwmon.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c index a34753fc29733..6040a89406743 100644 --- a/drivers/hwmon/dell-smm-hwmon.c +++ b/drivers/hwmon/dell-smm-hwmon.c @@ -76,6 +76,9 @@ #define DELL_SMM_NO_TEMP 10 #define DELL_SMM_NO_FANS 4 +/* limit fan multiplier to avoid overflow */ +#define DELL_SMM_MAX_FAN_MULT (INT_MAX / U16_MAX) + struct smm_regs { unsigned int eax; unsigned int ebx; @@ -1253,6 +1256,12 @@ static int dell_smm_init_data(struct device *dev, const struct dell_smm_ops *ops data->ops = ops; /* All options must not be 0 */ data->i8k_fan_mult = fan_mult ? : I8K_FAN_MULT; + if (data->i8k_fan_mult > DELL_SMM_MAX_FAN_MULT) { + dev_err(dev, + "fan multiplier %u is too large (max %u)\n", + data->i8k_fan_mult, DELL_SMM_MAX_FAN_MULT); + return -EINVAL; + } data->i8k_fan_max = fan_max ? : I8K_FAN_HIGH; data->i8k_pwm_mult = DIV_ROUND_UP(255, data->i8k_fan_max); -- 2.47.3