Re: [PATCH] x86/PoD: correct ordering of checks in p2m_pod_zero_check()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 07/04/2020 12:07, Jan Beulich wrote:
> Commit 0537d246f8db ("mm: add 'is_special_page' inline function...")
> moved the is_special_page() checks first in its respective changes to
> PoD code. While this is fine for p2m_pod_zero_check_superpage(), the
> validity of the MFN is inferred in both cases from the p2m_is_ram()
> check, which therefore also needs to come first in this 2nd instance.
>
> Take the opportunity and address latent UB here as well - transform
> the MFN into struct page_info * only after having established that
> this is a valid page.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>