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From:   Marco Elver <elver@google.com>
Date:   Mon, 9 Oct 2023 10:45:40 +0200
Message-ID: <CANpmjNOHPRHOOPNwx04S_CE5OoQMAmfxHjxqeqy=YUpU+sY7yA@mail.gmail.com>
Subject: Re: [PATCH 3/5] kasan: use unchecked __memset internally
To:     andrey.konovalov@linux.dev
Cc:     Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        kasan-dev@googlegroups.com,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Andrey Konovalov <andreyknvl@google.com>
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On Fri, 6 Oct 2023 at 17:18, <andrey.konovalov@linux.dev> wrote:
>
> From: Andrey Konovalov <andreyknvl@google.com>
>
> KASAN code is supposed to use the unchecked __memset implementation when
> accessing its metadata.
>
> Change uses of memset to __memset in mm/kasan/.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Do we need a "Fixes" tag?

Reviewed-by: Marco Elver <elver@google.com>

> ---
>  mm/kasan/report.c | 4 ++--
>  mm/kasan/shadow.c | 2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index ca4b6ff080a6..12557ffee90b 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -538,7 +538,7 @@ void kasan_report_invalid_free(void *ptr, unsigned long ip, enum kasan_report_ty
>
>         start_report(&flags, true);
>
> -       memset(&info, 0, sizeof(info));
> +       __memset(&info, 0, sizeof(info));
>         info.type = type;
>         info.access_addr = ptr;
>         info.access_size = 0;
> @@ -576,7 +576,7 @@ bool kasan_report(const void *addr, size_t size, bool is_write,
>
>         start_report(&irq_flags, true);
>
> -       memset(&info, 0, sizeof(info));
> +       __memset(&info, 0, sizeof(info));
>         info.type = KASAN_REPORT_ACCESS;
>         info.access_addr = addr;
>         info.access_size = size;
> diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
> index dd772f9d0f08..d687f09a7ae3 100644
> --- a/mm/kasan/shadow.c
> +++ b/mm/kasan/shadow.c
> @@ -324,7 +324,7 @@ static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr,
>         if (!page)
>                 return -ENOMEM;
>
> -       memset((void *)page, KASAN_VMALLOC_INVALID, PAGE_SIZE);
> +       __memset((void *)page, KASAN_VMALLOC_INVALID, PAGE_SIZE);
>         pte = pfn_pte(PFN_DOWN(__pa(page)), PAGE_KERNEL);
>
>         spin_lock(&init_mm.page_table_lock);
> --
> 2.25.1
>