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Date:   Mon, 9 Oct 2023 17:00:31 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Haibo Li <haibo.li@mediatek.com>
Cc:     <linux-kernel@vger.kernel.org>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        <kasan-dev@googlegroups.com>, <linux-mm@kvack.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-mediatek@lists.infradead.org>, <xiaoming.yu@mediatek.com>
Subject: Re: [PATCH v2] kasan:print the original fault addr when access
 invalid shadow
Message-Id: <20231009170031.a294c11575d5d4941b8596a9@linux-foundation.org>
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On Mon, 9 Oct 2023 15:37:48 +0800 Haibo Li <haibo.li@mediatek.com> wrote:

> when the checked address is illegal,the corresponding shadow address
> from kasan_mem_to_shadow may have no mapping in mmu table.
> Access such shadow address causes kernel oops.
> Here is a sample about oops on arm64(VA 39bit) 
> with KASAN_SW_TAGS and KASAN_OUTLINE on:
> 
> [ffffffb80aaaaaaa] pgd=000000005d3ce003, p4d=000000005d3ce003,
>     pud=000000005d3ce003, pmd=0000000000000000
> Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
> Modules linked in:
> CPU: 3 PID: 100 Comm: sh Not tainted 6.6.0-rc1-dirty #43
> Hardware name: linux,dummy-virt (DT)
> pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : __hwasan_load8_noabort+0x5c/0x90
> lr : do_ib_ob+0xf4/0x110
> ffffffb80aaaaaaa is the shadow address for efffff80aaaaaaaa.
> The problem is reading invalid shadow in kasan_check_range.
> 
> The generic kasan also has similar oops.
> 
> It only reports the shadow address which causes oops but not
> the original address.
> 
> Commit 2f004eea0fc8("x86/kasan: Print original address on #GP")
> introduce to kasan_non_canonical_hook but limit it to KASAN_INLINE.
> 
> This patch extends it to KASAN_OUTLINE mode.

Is 2f004eea0fc8 a suitable Fixes: target for this?  If not, what is?

Also, I'm assuming that we want to backport this fix into earlier
kernel versions?