Re: [PATCH] mm/vmalloc: unbreak kasan vmalloc support

From: David Gow
Date: Thu Jun 17 2021 - 04:44:05 EST

On Thu, Jun 17, 2021 at 4:13 PM Daniel Axtens <dja@xxxxxxxxxx> wrote:
> In commit 121e6f3258fe ("mm/vmalloc: hugepage vmalloc mappings"),
> __vmalloc_node_range was changed such that __get_vm_area_node was no
> longer called with the requested/real size of the vmalloc allocation, but
> rather with a rounded-up size.
> This means that __get_vm_area_node called kasan_unpoision_vmalloc() with
> a rounded up size rather than the real size. This led to it allowing
> access to too much memory and so missing vmalloc OOBs and failing the
> kasan kunit tests.
> Pass the real size and the desired shift into __get_vm_area_node. This
> allows it to round up the size for the underlying allocators while
> still unpoisioning the correct quantity of shadow memory.
> Adjust the other call-sites to pass in PAGE_SHIFT for the shift value.
> Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
> Cc: David Gow <davidgow@xxxxxxxxxx>
> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
> Cc: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
> Link:
> Fixes: 121e6f3258fe ("mm/vmalloc: hugepage vmalloc mappings")
> Signed-off-by: Daniel Axtens <dja@xxxxxxxxxx>
> ---

This fixes the KUnit test failure I was seeing on x86_64, thanks!

Tested-by: David Gow <davidgow@xxxxxxxxxx>

-- David