linux-kernel - Re: [PATCH] mm/vmalloc: unbreak kasan vmalloc support

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Message-ID: <CABVgOSmYiVA008enEkGy4XTooVQ7DftXvWySFLL16bZETocpqg@mail.gmail.com>
Date:   Thu, 17 Jun 2021 16:43:49 +0800
From:   David Gow <davidgow@...gle.com>
To:     Daniel Axtens <dja@...ens.net>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Uladzislau Rezki <urezki@...il.com>
Subject: Re: [PATCH] mm/vmalloc: unbreak kasan vmalloc support

On Thu, Jun 17, 2021 at 4:13 PM Daniel Axtens <dja@...ens.net> 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@...il.com>
> Cc: David Gow <davidgow@...gle.com>
> Cc: Dmitry Vyukov <dvyukov@...gle.com>
> Cc: Andrey Konovalov <andreyknvl@...il.com>
> Cc: Uladzislau Rezki (Sony) <urezki@...il.com>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=213335
> Fixes: 121e6f3258fe ("mm/vmalloc: hugepage vmalloc mappings")
> Signed-off-by: Daniel Axtens <dja@...ens.net>
> ---

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

Tested-by: David Gow <davidgow@...gle.com>

Cheers,
-- David