CVE-2026-74513 dibs: fix use-after-free of dmb_node in loopback attach/detach/unregister

In the Linux kernel, the following vulnerability has been resolved: dibs: fix use-after-free of dmbnode in loopback attach/detach/unregister dibsloattachdmb, dibslodetachdmb and dibslounregisterdmb look up the dmbnode under dmbhtlock, drop the lock and only then operate on the node's refcount...