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From:   Kees Cook <keescook@chromium.org>
Date:   Wed, 27 Jun 2018 14:48:10 -0700
Message-ID: <CAGXu5j+Su3fObnuzntQ7Tp8W6jfMt1hc=h-3Xhidgx--Nau1Ew@mail.gmail.com>
Subject: Re: [PATCH] dm: writecache: Use 2-factor allocator arguments
To:     Mikulas Patocka <mpatocka@redhat.com>
Cc:     LKML <linux-kernel@vger.kernel.org>, dm-devel@redhat.com,
        Dan Williams <dan.j.williams@intel.com>,
        Mike Snitzer <msnitzer@redhat.com>,
        Alasdair Kergon <agk@redhat.com>
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Sender: linux-kernel-owner@vger.kernel.org
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On Mon, Jun 18, 2018 at 10:50 AM, Kees Cook <keescook@chromium.org> wrote:
> This adjusts the allocator calls to use the 2-factor argument style, as
> already done treewide for better defense against allocator overflows.
> Additionally adjusts style nit to avoid assignments in test expressions.
>
> Signed-off-by: Kees Cook <keescook@chromium.org>

Friendly ping -- I'd like to make sure this makes it into 4.18. All
other 2-factor allocations have been fixed in the kernel.

-Kees

> ---
>  drivers/md/dm-writecache.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
> index 5961c7794ef3..7773f4c75701 100644
> --- a/drivers/md/dm-writecache.c
> +++ b/drivers/md/dm-writecache.c
> @@ -259,7 +259,7 @@ static int persistent_memory_claim(struct dm_writecache *wc)
>         if (da != p) {
>                 long i;
>                 wc->memory_map = NULL;
> -               pages = kvmalloc(p * sizeof(struct page *), GFP_KERNEL);
> +               pages = kvmalloc_array(p, sizeof(struct page *), GFP_KERNEL);
>                 if (!pages) {
>                         r = -ENOMEM;
>                         goto err2;
> @@ -859,7 +859,8 @@ static int writecache_alloc_entries(struct dm_writecache *wc)
>
>         if (wc->entries)
>                 return 0;
> -       wc->entries = vmalloc(sizeof(struct wc_entry) * wc->n_blocks);
> +       wc->entries = vmalloc(array_size(sizeof(struct wc_entry),
> +                                        wc->n_blocks));
>         if (!wc->entries)
>                 return -ENOMEM;
>         for (b = 0; b < wc->n_blocks; b++) {
> @@ -1480,10 +1481,13 @@ static void __writecache_writeback_pmem(struct dm_writecache *wc, struct writeba
>                 bio_set_dev(&wb->bio, wc->dev->bdev);
>                 wb->bio.bi_iter.bi_sector = read_original_sector(wc, e);
>                 wb->page_offset = PAGE_SIZE;
> -               if (max_pages <= WB_LIST_INLINE ||
> -                   unlikely(!(wb->wc_list = kmalloc(max_pages * sizeof(struct wc_entry *),
> -                                                    GFP_NOIO | __GFP_NORETRY |
> -                                                    __GFP_NOMEMALLOC | __GFP_NOWARN)))) {
> +               if (max_pages > WB_LIST_INLINE)
> +                       wb->wc_list = kmalloc_array(max_pages,
> +                                                   sizeof(struct wc_entry *),
> +                                                   GFP_NOIO | __GFP_NORETRY |
> +                                                   __GFP_NOMEMALLOC |
> +                                                   __GFP_NOWARN);
> +               if (max_pages <= WB_LIST_INLINE || !wb->wc_list) {
>                         wb->wc_list = wb->wc_list_inline;
>                         max_pages = WB_LIST_INLINE;
>                 }
> --
> 2.17.0
>
>
> --
> Kees Cook
> Pixel Security


-- 
Kees Cook
Pixel Security