NX开启状态

$ checksec vuln
[*] '~/vuln'
    Arch:     amd64-64-little
    RELRO:    Partial RELRO
    Stack:    No canary found
    NX:       NX enabled
    PIE:      No PIE (0x400000)

the NX bit. The NX bit has the effect of preventing memory areas not supposed to contain code (typically, the stack) from being executed

ROP

mprotect

sigreturn