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

[PATCH] qtnfmac: 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 code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/net/wireless/quantenna/qtnfmac/commands.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/quantenna/qtnfmac/commands.c b/drivers/net/wireless/quantenna/qtnfmac/commands.c
index 659e7649fe22..cf386f579060 100644
--- a/drivers/net/wireless/quantenna/qtnfmac/commands.c
+++ b/drivers/net/wireless/quantenna/qtnfmac/commands.c
@@ -914,9 +914,8 @@ qtnf_cmd_resp_proc_hw_info(struct qtnf_bus *bus,
 	if (WARN_ON(resp->n_reg_rules > NL80211_MAX_SUPP_REG_RULES))
 		return -E2BIG;
 
-	hwinfo->rd = kzalloc(sizeof(*hwinfo->rd)
-			     + sizeof(struct ieee80211_reg_rule)
-			     * resp->n_reg_rules, GFP_KERNEL);
+	hwinfo->rd = kzalloc(struct_size(hwinfo->rd, reg_rules,
+					 resp->n_reg_rules), GFP_KERNEL);
 
 	if (!hwinfo->rd)
 		return -ENOMEM;
-- 
2.20.1

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

[Sergey Matyukevich]

> 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[];
> };

...

> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
>  drivers/net/wireless/quantenna/qtnfmac/commands.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/wireless/quantenna/qtnfmac/commands.c b/drivers/net/wireless/quantenna/qtnfmac/commands.c
> index 659e7649fe22..cf386f579060 100644
> --- a/drivers/net/wireless/quantenna/qtnfmac/commands.c
> +++ b/drivers/net/wireless/quantenna/qtnfmac/commands.c
> @@ -914,9 +914,8 @@ qtnf_cmd_resp_proc_hw_info(struct qtnf_bus *bus,
>         if (WARN_ON(resp->n_reg_rules > NL80211_MAX_SUPP_REG_RULES))
>                 return -E2BIG;
> 
> -       hwinfo->rd = kzalloc(sizeof(*hwinfo->rd)
> -                            + sizeof(struct ieee80211_reg_rule)
> -                            * resp->n_reg_rules, GFP_KERNEL);
> +       hwinfo->rd = kzalloc(struct_size(hwinfo->rd, reg_rules,
> +                                        resp->n_reg_rules), GFP_KERNEL);
> 
>         if (!hwinfo->rd)
>                 return -ENOMEM;

Thanks!

Reviewed-by: Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>

Regards,
Sergey

Re: [PATCH] qtnfmac: 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 code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> Reviewed-by: Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>

Patch applied to wireless-drivers-next.git, thanks.

db040dfa53e2 qtnfmac: use struct_size() in kzalloc()

-- 
https://patchwork.kernel.org/patch/10752601/

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