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 <20210303152355.fa7c3bcb02862ceefea5ca45@linux-foundation.org>
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From:   Andrey Konovalov <andreyknvl@google.com>
Date:   Fri, 5 Mar 2021 16:43:11 +0100
Message-ID: <CAAeHK+yVG0-36TUpH8EkQ7r1DHNGTHuOfLfKBKO3aDtCV0RnRQ@mail.gmail.com>
Subject: Re: [PATCH] kasan, mm: fix crash with HW_TAGS and DEBUG_PAGEALLOC
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Marco Elver <elver@google.com>,
        Peter Collingbourne <pcc@google.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>,
        Kevin Brodsky <kevin.brodsky@arm.com>,
        Christoph Hellwig <hch@infradead.org>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        stable <stable@vger.kernel.org>
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On Thu, Mar 4, 2021 at 12:23 AM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Fri, 26 Feb 2021 02:25:37 +0100 Andrey Konovalov <andreyknvl@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@vger.kernel.org>