tree 33bb487fb4c8b5935bd38a47d6d2514da23e328b
parent 2a0e0a35002db7ac64f4e82ea2a4ad2fb6d934b0
author Zhao Liu <zhao1.liu@intel.com> 1708678608 +0800
committer Michael S. Tsirkin <mst@redhat.com> 1710280615 -0400

hw/display/macfb: Fix missing ERRP_GUARD() in macfb_nubus_realize()

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.
...
* 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.

But in macfb_nubus_realize(), @errp is dereferenced without
ERRP_GUARD():

ndc->parent_realize(dev, errp);
if (*errp) {
    return;
}

Here we check *errp, because the ndc->parent_realize(), as a
DeviceClass.realize() callback, returns void. And since
macfb_nubus_realize(), also as a DeviceClass.realize(), doesn't get the
NULL @errp parameter, it hasn't triggered the bug that dereferencing the
NULL @errp.

To follow the requirement of @errp, add missing ERRP_GUARD() in
macfb_nubus_realize().

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20240223085653.1255438-3-zhao1.liu@linux.intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>