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    SubjectRe: [PATCH v3 2/3] platform/x86: wmi: add WMI support to MODULE_DEVICE_TABLE()
    On Sun, Feb 3, 2019 at 9:04 PM Mattias Jacobsson <2pi@mok.nu> wrote:
    > On 2019-01-30, Andy Shevchenko wrote:
    > > On Wed, Jan 30, 2019 at 5:15 PM Mattias Jacobsson <2pi@mok.nu> wrote:

    > > > + if (len < 0 || len >= 500) {
    > >
    > > Would it even possible to get a negative number here?
    > > Same for any other number than slightly bigger than 36.
    >
    > snprintf returns a negative number on error. BTW AFAIU the code from
    > file2alias.c gets dynamically linked against a libc.

    OK.

    > > So, what about simple
    > >
    > > {
    > > DEF_FIELD_ADDR(...);
    > > size_t len;
    > >
    > > len = strlen(*guid_string);
    > > if (len != ...) {
    > > ...
    > > }
    > > sprintf(...);
    > > return 1;
    > > }
    > >
    > > ?
    >
    > Then we are missing the check that we are within the bounds of alias

    I don't see how. By checking a length of string we be sure, that the
    result would have a non-arbitrary length.

    > as well as the negative code from s*printf(). snprintf() does this nicely
    > for us.

    This one I agree with, means in the above example we may do

    return sprintf(...);

    if callers recognize just a sign, or

    len = sprintf(...);
    if (len < 0)
    return len; // -1? 0?

    return 1;

    otherwise.

    --
    With Best Regards,
    Andy Shevchenko

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