linux-kernel - Re: [PATCH] ath10k: use struct

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Date:   Thu, 23 Aug 2018 19:59:51 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        ath10k@...ts.infradead.org,
        linux-wireless <linux-wireless@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ath10k: use struct_size() in kzalloc()

On Thu, Aug 23, 2018 at 6:12 PM, Gustavo A. R. Silva
<gustavo@...eddedor.com> wrote:
> One of the more common cases of allocation size calculations is finding
> the size of a structure that has a zero-sized array at the end, along
> with memory for some number of elements for that array. For example:
>
> struct foo {
>         int stuff;
>         void *entry[];
> };
>
> instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);
>
> Instead of leaving these open-coded and prone to type mistakes, we can
> now use the new struct_size() helper:
>
> instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);
>
> This issue was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>

Reviewed-by: Kees Cook <keescook@...omium.org>

-Kees

> ---
>  drivers/net/wireless/ath/ath10k/ce.c | 24 ++++++++----------------
>  1 file changed, 8 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath10k/ce.c b/drivers/net/wireless/ath/ath10k/ce.c
> index 18c709c..d0381aa 100644
> --- a/drivers/net/wireless/ath/ath10k/ce.c
> +++ b/drivers/net/wireless/ath/ath10k/ce.c
> @@ -1416,10 +1416,8 @@ ath10k_ce_alloc_src_ring(struct ath10k *ar, unsigned int ce_id,
>
>         nentries = roundup_pow_of_two(nentries);
>
> -       src_ring = kzalloc(sizeof(*src_ring) +
> -                          (nentries *
> -                           sizeof(*src_ring->per_transfer_context)),
> -                          GFP_KERNEL);
> +       src_ring = kzalloc(struct_size(src_ring, per_transfer_context,
> +                                      nentries), GFP_KERNEL);
>         if (src_ring == NULL)
>                 return ERR_PTR(-ENOMEM);
>
> @@ -1476,10 +1474,8 @@ ath10k_ce_alloc_src_ring_64(struct ath10k *ar, unsigned int ce_id,
>
>         nentries = roundup_pow_of_two(nentries);
>
> -       src_ring = kzalloc(sizeof(*src_ring) +
> -                          (nentries *
> -                           sizeof(*src_ring->per_transfer_context)),
> -                          GFP_KERNEL);
> +       src_ring = kzalloc(struct_size(src_ring, per_transfer_context,
> +                                      nentries), GFP_KERNEL);
>         if (!src_ring)
>                 return ERR_PTR(-ENOMEM);
>
> @@ -1534,10 +1530,8 @@ ath10k_ce_alloc_dest_ring(struct ath10k *ar, unsigned int ce_id,
>
>         nentries = roundup_pow_of_two(attr->dest_nentries);
>
> -       dest_ring = kzalloc(sizeof(*dest_ring) +
> -                           (nentries *
> -                            sizeof(*dest_ring->per_transfer_context)),
> -                           GFP_KERNEL);
> +       dest_ring = kzalloc(struct_size(dest_ring, per_transfer_context,
> +                                       nentries), GFP_KERNEL);
>         if (dest_ring == NULL)
>                 return ERR_PTR(-ENOMEM);
>
> @@ -1580,10 +1574,8 @@ ath10k_ce_alloc_dest_ring_64(struct ath10k *ar, unsigned int ce_id,
>
>         nentries = roundup_pow_of_two(attr->dest_nentries);
>
> -       dest_ring = kzalloc(sizeof(*dest_ring) +
> -                           (nentries *
> -                            sizeof(*dest_ring->per_transfer_context)),
> -                           GFP_KERNEL);
> +       dest_ring = kzalloc(struct_size(dest_ring, per_transfer_context,
> +                                       nentries), GFP_KERNEL);
>         if (!dest_ring)
>                 return ERR_PTR(-ENOMEM);
>
> --
> 2.7.4
>



-- 
Kees Cook
Pixel Security