[PATCH] kasan, mm: fix crash with HW_TAGS and DEBUG_PAGEALLOC

[Andrey Konovalov]

On Thu, Mar 4, 2021 at 12:23 AM Andrew Morton <akpm at linux-foundation.org> wrote:
>
> On Fri, 26 Feb 2021 02:25:37 +0100 Andrey Konovalov <andreyknvl at google.com> wrote:
>
> > Currently, kasan_free_nondeferred_pages()->kasan_free_pages() is called
> > after debug_pagealloc_unmap_pages(). This causes a crash when
> > debug_pagealloc is enabled, as HW_TAGS KASAN can't set tags on an
> > unmapped page.
> >
> > This patch puts kasan_free_nondeferred_pages() before
> > debug_pagealloc_unmap_pages().
> >
> > Besides fixing the crash, this also makes the annotation order consistent
> > with debug_pagealloc_map_pages() preceding kasan_alloc_pages().
> >
>
> This bug exists in 5.12, does it not?
>
> If so, is cc:stable appropriate and if so, do we have a suitable Fixes:
> commit?

Sure:

Fixes: 94ab5b61ee16  ("kasan, arm64: enable CONFIG_KASAN_HW_TAGS")
Cc: <stable at vger.kernel.org>