How to push a 64bit int in NASM?

Question

I\'m trying to push a 64bit integer but when assembling NASM seems to want to see it as a DWORD not a QWORD.

I\'m using ASM to create the shellcode I need to inject

Answer 1

There is no push imm64 instruction. As a workaround you can do one of the following:

1. go through a register: mov rax, 0xACEACEACACEACEAC; push rax
2. go through memory: push qword [rel foo]
3. write it in two parts: push dword low32; mov dword [rsp+4], high32 or sub rsp,8; mov dword [rsp], low32; mov dword [rsp+4], high32
4. use sign-extension if your immediate allows it