netdev - Re: [ethtool PATCH] netlink: fix -Walloc-size

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Date: Mon, 27 Nov 2023 16:46:17 +0100
From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
To: Sam James <sam@...too.org>, <netdev@...r.kernel.org>
Subject: Re: [ethtool PATCH] netlink: fix -Walloc-size

On 11/25/23 00:08, Sam James wrote:
> GCC 14 introduces a new -Walloc-size included in -Wextra which gives:

Nice :)

> ```
> netlink/strset.c: In function ‘get_perdev_by_ifindex’:
> netlink/strset.c:121:16: warning: allocation of insufficient size ‘1’ for type ‘struct perdev_strings’ with size ‘648’ [-Walloc-size]
>    121 |         perdev = calloc(sizeof(*perdev), 1);
>        |                ^
> ```
> 
> The calloc prototype is:
> ```
> void *calloc(size_t nmemb, size_t size);
> ```
> 
> So, just swap the number of members and size arguments to match the prototype, as
> we're initialising 1 struct of size `sizeof(*perdev)`. GCC then sees we're not
> doing anything wrong. This is consistent with other use in the codebase too.
> 
> Signed-off-by: Sam James <sam@...too.org>
> ---
>   netlink/strset.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/netlink/strset.c b/netlink/strset.c
> index fbc9c17..949d597 100644
> --- a/netlink/strset.c
> +++ b/netlink/strset.c
> @@ -118,7 +118,7 @@ static struct perdev_strings *get_perdev_by_ifindex(int ifindex)
>   		return perdev;
>   
>   	/* not found, allocate and insert into list */
> -	perdev = calloc(sizeof(*perdev), 1);
> +	perdev = calloc(1, sizeof(*perdev));
>   	if (!perdev)
>   		return NULL;
>   	perdev->ifindex = ifindex;

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@...el.com>