linux-kernel - Re: [PATCH v2 1/1] mm: kfence: apply kmemleak_ignore

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Message-ID: <CAMuHMdX=MTsmo5ZVa8ya3xmr4Mx7f0PB3gvFF42pdaTYB6-u5A@mail.gmail.com>
Date:   Fri, 15 Jul 2022 10:17:43 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     yee.lee@...iatek.com
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Alexander Potapenko <glider@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "open list:KFENCE" <kasan-dev@...glegroups.com>,
        "open list:MEMORY MANAGEMENT" <linux-mm@...ck.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH v2 1/1] mm: kfence: apply kmemleak_ignore_phys on early
 allocated pool

Hi Yee,

On Tue, Jun 28, 2022 at 1:42 PM <yee.lee@...iatek.com> wrote:
> From: Yee Lee <yee.lee@...iatek.com>
>
> This patch solves two issues.
>
> (1) The pool allocated by memblock needs to unregister from
> kmemleak scanning. Apply kmemleak_ignore_phys to replace the
> original kmemleak_free as its address now is stored in the phys tree.
>
> (2) The pool late allocated by page-alloc doesn't need to unregister.
> Move out the freeing operation from its call path.
>
> Suggested-by: Catalin Marinas <catalin.marinas@....com>
> Suggested-by: Marco Elver <elver@...gle.com>
> Signed-off-by: Yee Lee <yee.lee@...iatek.com>

Thank you, this fixes the storm of

    BUG: KFENCE: invalid read in scan_block+0x78/0x130
    BUG: KFENCE: use-after-free read in scan_block+0x78/0x130
    BUG: KFENCE: out-of-bounds read in scan_block+0x78/0x130

messages I was seeing on arm64.

Tested-by: Geert Uytterhoeven <geert+renesas@...der.be>

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds