This patch fixes the following for messagebox.rb
Issue 1 (#4415)
When exitfunc is none, the payload will not be able to generate
due to an "invalid opcode" error.
Issue 2: (#4414)
After "user32.dll" is pushed onto the stack for the LoadLibrary
call, the payload does not actually ensure bl is a null byte, it
just assumes it is and uses it to modify the stack to get a
null-terminated string.
Fix#4414Fix#4415
2c0c732967