Kernel panic via misaligned RISC-V kprobe

Denial of service in affected Linux kernels on RISC-V allows local users to panic the kernel by registering a kprobe at an illegal position. The RISC-V arch_prepare_kprobe path installs an ebreak without first rejecting an address in the middle of an instruction, corrupting the original instruction stream. Reachability requires local access to kprobe_events on a RISC-V kernel with kprobes enabled; the demonstrated result is a kernel panic, not data access.