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

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Message-ID: <671185b9-5c91-5235-b5ea-96d3449bf716@embeddedor.com>
Date:   Wed, 28 Aug 2019 13:29:16 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>
Cc:     linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ima: use struct_size() in kzalloc()

Hi all,

Friendly ping:

Who can take this, please?

Thanks
--
Gustavo

On 5/29/19 11:53 AM, Gustavo A. R. Silva 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;
>    struct boo entry[];
> };
> 
> instance = kzalloc(sizeof(struct foo) + count * sizeof(struct boo), 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@...eddedor.com>
> ---
>  security/integrity/ima/ima_template.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
> index b631b8bc7624..b945dff2ed14 100644
> --- a/security/integrity/ima/ima_template.c
> +++ b/security/integrity/ima/ima_template.c
> @@ -281,9 +281,8 @@ static int ima_restore_template_data(struct ima_template_desc *template_desc,
>  	int ret = 0;
>  	int i;
>  
> -	*entry = kzalloc(sizeof(**entry) +
> -		    template_desc->num_fields * sizeof(struct ima_field_data),
> -		    GFP_NOFS);
> +	*entry = kzalloc(struct_size(*entry, template_data,
> +				     template_desc->num_fields), GFP_NOFS);
>  	if (!*entry)
>  		return -ENOMEM;
>  
>