On Tue, 24 Jan 2023 21:35:26 +0100 andrey.konovalov@xxxxxxxxx wrote:
> The implementation of page_alloc poisoning sampling assumed that
> tag_clear_highpage resets page tags for __GFP_ZEROTAGS allocations.
> However, this is no longer the case since commit 70c248aca9e7
> ("mm: kasan: Skip unpoisoning of user pages").
>
> This leads to kernel crashes when MTE-enabled userspace mappings are
> used with Hardware Tag-Based KASAN enabled.
>
> Reset page tags for __GFP_ZEROTAGS allocations in post_alloc_hook().
>
> Also clarify and fix related comments.
I assume this is a fix against 44383cef54c0 ("kasan: allow sampling
page_alloc allocations for HW_TAGS") which is presently in mm-stable,
yes?
