6.12-stable review patch. If anyone has any objections, please let me know.
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From: Denis Sergeev denserg.edu@gmail.com
[ Upstream commit 46c28bbbb150b80827e4bcbea231560af9d16854 ]
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 denserg.edu@gmail.com Link: https://lore.kernel.org/r/20251209063706.49008-1-denserg.edu@gmail.com Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Sasha Levin sashal@kernel.org --- 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 f73f46193748..9df78861f5f8 100644 --- a/drivers/hwmon/dell-smm-hwmon.c +++ b/drivers/hwmon/dell-smm-hwmon.c @@ -75,6 +75,9 @@ #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; @@ -1203,6 +1206,12 @@ 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);