Potential security issue by disabling W^X in the original function and the jit memory

[ZzzMao]

For functions in the memory, we usually have W^X protection to avoid buffer overflow attacking.

In the patch_function, it disabled the W^X first to be able to inject code to the original function address:

pub(crate) unsafe fn patch_function(func: *mut u8, patch: &[u8]) {
    make_memory_writable_and_executable(func); // <--------- HERE

    inject_asm_code(patch, func);
}

Should we consider doing it like this:

• Change the memory page to Writable only (or Writable and Executable)
• Inject the code.
• Change the memory page to Executable only.

This idea also applies to the allocate_jit_memory.