[PATCH] ath10k: use struct_size() in kzalloc()

[PATCH] ath10k: use struct_size() in kzalloc()

[Gustavo A. R. Silva]

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@embeddedor.com>
---
 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

Re: [PATCH] ath10k: use struct_size() in kzalloc()

[Kees Cook]

On Thu, Aug 23, 2018 at 6:12 PM, Gustavo A. R. Silva
<gustavo@embeddedor.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@embeddedor.com>

Reviewed-by: Kees Cook <keescook@chromium.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

Re: [PATCH] ath10k: use struct_size() in kzalloc()

[Kalle Valo]

"Gustavo A. R. Silva" <gustavo@embeddedor.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@embeddedor.com>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

Patch applied to ath-next branch of ath.git, thanks.

06ae8dc00433 ath10k: use struct_size() in kzalloc()

-- 
https://patchwork.kernel.org/patch/10574741/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches