IonStack part II: GhostLock, a stack-UAF that has existed in ALL Linux distributions for 15 years

Technical disclosure July 7, 2026. Stack UAF in remove_waiter() — cleans wrong task on requeue path. 97% stable LPE and container escape. Affected v2.6.39-rc1 to v7.1-rc1, CONFIG_FUTEX_PI=y only. Fix: commit 3bfdc63936dd.