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    SubjectRe: [PATCH v2 1/2] i8k: Autodetect maximal fan speed and fan RPM multiplier
    Date
    On Friday 19 December 2014 19:32:37 Guenter Roeck wrote:
    > > -static int i8k_fan_mult;
    > > -static int i8k_pwm_mult;
    > > -static int i8k_fan_max = I8K_FAN_HIGH;
    > > +static int i8k_fan_mult[2];
    > > +static int i8k_pwm_mult[2];
    > > +static int i8k_fan_max[2];
    >
    > The rationale for this change is not explained in the commit
    > log.
    >
    > Do you have any indication that those values would ever be
    > different for the two fans, ie that you actually need arrays
    > here ?
    >

    I do not know... But if we decide to use only single value for
    multiplier and max value which fan to use for autodetection?

    > > @@ -271,8 +274,25 @@ static int i8k_get_fan_speed(int fan)
    > >
    > > {
    > >
    > > struct smm_regs regs = { .eax = I8K_SMM_GET_SPEED, };
    > >
    > > + if (fan < 0 || fan >= ARRAY_SIZE(i8k_fan_mult))
    > > + return -EINVAL;
    > > +
    >
    > This range check (and probably others) is still unnecessary.
    >
    > Guenter
    >

    No, it is necessary. Function i8k_get_fan_speed is called from
    ioctl callback with value which comes from userspace. If
    userspace specify fan out of that array we can get kernel panic.

    > > regs.ebx = fan & 0xff;
    > >
    > > - return i8k_smm(&regs) ? : (regs.eax & 0xffff) *
    > > i8k_fan_mult; + return i8k_smm(&regs) ? : (regs.eax &
    > > 0xffff) * i8k_fan_mult[fan]; +}

    --
    Pali Rohár
    pali.rohar@gmail.com
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