Zhao Liu <zhao1....@linux.intel.com> writes:
> From: Zhao Liu <zhao1....@intel.com>
>
> As the comment in qapi/error, dereferencing @errp requires
> ERRP_GUARD():
>
> * = Why, when and how to use ERRP_GUARD() =
> *
> * Without ERRP_GUARD(), use of the @errp parameter is restricted:
> * - It must not be dereferenced, because it may be null.
> * - It should not be passed to error_prepend() or
> * error_append_hint(), because that doesn't work with &error_fatal.
> * ERRP_GUARD() lifts these restrictions.
> *
> * To use ERRP_GUARD(), add it right at the beginning of the function.
> * @errp can then be used without worrying about the argument being
> * NULL or &error_fatal.
> *
> * Using it when it's not needed is safe, but please avoid cluttering
> * the source with useless code.
>
> Currently, since macfb_nubus_realize() - as a DeviceClass.realize()
> method - doesn't get the NULL errp parameter, it doesn't trigger the
> dereference issue.
>
> To follow the requirement of errp, add missing ERRP_GUARD() in
> macfb_nubus_realize().
>
> Suggested-by: Markus Armbruster <arm...@redhat.com>
> Signed-off-by: Zhao Liu <zhao1....@intel.com>
> ---
> Suggested by credit:
> Markus: Referred his explanation about ERRP_GUARD().
> ---
> hw/display/macfb.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/hw/display/macfb.c b/hw/display/macfb.c
> index 418e99c8e18e..1ace341a0ff4 100644
> --- a/hw/display/macfb.c
> +++ b/hw/display/macfb.c
> @@ -714,6 +714,7 @@ static void macfb_nubus_set_irq(void *opaque, int n, int
> level)
>
> static void macfb_nubus_realize(DeviceState *dev, Error **errp)
> {
> + ERRP_GUARD();
> NubusDevice *nd = NUBUS_DEVICE(dev);
> MacfbNubusState *s = NUBUS_MACFB(dev);
> MacfbNubusDeviceClass *ndc = NUBUS_MACFB_GET_CLASS(dev);
The dereference is
ndc->parent_realize(dev, errp);
if (*errp) {
return;
}
We check *errp, because neither the callback returns void.
Reviewed-by: Markus Armbruster <arm...@redhat.com>
