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From:   Marco Elver <elver@google.com>
Date:   Wed, 16 Feb 2022 20:31:29 +0100
Message-ID: <CANpmjNP0QCMhSL+ePf5G8UwbmdjM-qpimAQbuQD+pYK8Gx+2Gw@mail.gmail.com>
Subject: Re: [PATCH mm] kasan: print virtual mapping info in reports
To:     andrey.konovalov@linux.dev
Cc:     Alexander Potapenko <glider@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        kasan-dev@googlegroups.com,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Andrey Konovalov <andreyknvl@google.com>
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On Wed, 16 Feb 2022 at 20:01, <andrey.konovalov@linux.dev> wrote:
>
> From: Andrey Konovalov <andreyknvl@google.com>
>
> Print virtual mapping range and its creator in reports affecting virtual
> mappings.
>
> Also get physical page pointer for such mappings, so page information
> gets printed as well.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
>
> ---
>
> Note: no need to merge this patch into any of the KASAN vmalloc patches
> that are already in mm, better to keep it separate.
> ---
>  mm/kasan/report.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 137c2c0b09db..8002fb3c417d 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -260,8 +260,18 @@ static void print_address_description(void *addr, u8 tag)
>                 pr_err(" %pS\n", addr);
>         }
>
> +       if (is_vmalloc_addr(addr)) {
> +               struct vm_struct *va = find_vm_area(addr);
> +
> +               pr_err("The buggy address belongs to the virtual mapping at\n"
> +                      " [%px, %px) created by:\n"
> +                      " %pS\n", va->addr, va->addr + va->size, va->caller);

Can you show an example of what this looks like? It's not showing a
stack trace, so why not continue the line and just say "... created
by: %pS\n"

> +               page = vmalloc_to_page(page);
> +       }
> +
>         if (page) {
> -               pr_err("The buggy address belongs to the page:\n");
> +               pr_err("The buggy address belongs to the physical page:\n");
>                 dump_page(page, "kasan: bad access detected");
>         }
>
> --
> 2.25.1
>