Local privilege escalation via oversized user addresses

Kernel memory corruption in Linux on 64-bit RISC-V systems allows local users to gain privileges via crafted virtual addresses. The RISC-V __access_ok() boundary uses LONG_MAX, so get_user_pages_fast() accepts addresses above TASK_SIZE and can pin kernel pages for reads or writes. Any unprivileged local user can reach the deterministic path through syscalls such as futex, read, write, or io_uring, enabling kernel-memory disclosure, arbitrary kernel writes, privilege escalation, or a kernel panic.