On 2026/01/04 6:43, Joelle van Dyne wrote:
When `owner` == `mr`, `object_unparent` will crash:
object_unparent(mr) ->
object_property_del_child(mr, mr) ->
object_finalize_child_property(mr, name, mr) ->
object_unref(mr) ->
object_finalize(mr) ->
object_property_del_all(mr) ->
object_finalize_child_property(mr, name, mr) ->
object_unref(mr) ->
fail on g_assert(obj->ref > 0)
However, passing a different `owner` to `memory_region_init` does not
work. `memory_region_ref` has an optimization where it takes a ref
only on the owner. That means when flatviews are created, it does not
take a ref on the region and you can get a UAF from `flatview_destroy`
called from RCU.
The correct fix therefore is to use `NULL` as the name which will set
the `owner` but not the `parent` (which is still NULL). This allows us
to use `memory_region_ref` on itself while not having to rely on unparent
for cleanup.
Signed-off-by: Joelle van Dyne <[email protected]>
Reviewed-by: Akihiko Odaki <[email protected]>
