Could you please do this instead to not leak a few bytes of memory (and make the code more readable)?

    /* Enable events by default */
    ...

    /* Enable per-model events */

    if (maker == NULL || product == NULL)
        goto out;

    for (i = 0; i < nitems(acpi_ibm_models); i++) {
        ...
    }

out:
    freeenv(maker);
    freeenv(product);

The goto probably is more readable, but I don't think that it fixes a leak. The current patch still always calls freeenv() on both strings.

You're right.. I was thinking about an alternative method that isn't in place right now.