# \[kernel-hardening\] \[PATCH 4/6\] Protectable Memory

- From: Kees Cook \<hidden\>
- Date: 2018-02-13 21:43:49 
- List: linux-security-module
- Page: https://ratatoskr.run/linux-security-module/2018/02/5197646
- Thread: https://ratatoskr.run/linux-security-module/2018/01/5184248/t.md

```text
On Tue, Feb 13, 2018 at 8:09 AM, Laura Abbott [ref] wrote:
> No, arm64 doesn't fixup the aliases, mostly because arm64 uses larger
> page sizes which can't be broken down at runtime. CONFIG_PAGE_POISONING
> does use 4K pages which could be adjusted at runtime. So yes, you are
> right we would have physmap exposure on arm64 as well.

Errr, so that means even modules and kernel code are writable via the
arm64 physmap? That seems extraordinarily bad. :(

-Kees

-- 
Kees Cook
Pixel Security
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