On Tue, Nov 30, 2021 at 10:41 PM <andrey.konovalov@xxxxxxxxx> wrote:
>
> From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
>
> __GFP_ZEROTAGS should only be effective if memory is being zeroed.
> Currently, hardware tag-based KASAN violates this requirement.
>
> Fix by including an initialization check along with checking for
> __GFP_ZEROTAGS.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx>
> ---
> mm/kasan/hw_tags.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
> index 0b8225add2e4..c643740b8599 100644
> --- a/mm/kasan/hw_tags.c
> +++ b/mm/kasan/hw_tags.c
> @@ -199,11 +199,12 @@ void kasan_alloc_pages(struct page *page, unsigned int order, gfp_t flags)
> * page_alloc.c.
> */
> bool init = !want_init_on_free() && want_init_on_alloc(flags);
> + bool init_tags = init && (flags & __GFP_ZEROTAGS);
>
> if (flags & __GFP_SKIP_KASAN_POISON)
> SetPageSkipKASanPoison(page);
>
> - if (flags & __GFP_ZEROTAGS) {
> + if (init_tags) {
> int i;
>
> for (i = 0; i != 1 << order; ++i)
> --
> 2.25.1
>
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
Erika-Mann-Straße, 33
80636 München
Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
