Re: [PATCH] ima: Fix sizeof mismatches

[Colin Ian King <colin.king@canonical.com>]

On 12/10/2020 19:06, Joe Perches wrote:
> On Mon, 2020-10-12 at 13:51 -0400, Mimi Zohar wrote:
>> On Wed, 2020-10-07 at 11:27 -0700, Joe Perches wrote:
>>> On Wed, 2020-10-07 at 12:02 +0100, Colin King wrote:
>>>> An incorrect sizeof is being used, sizeof(*fields) is not correct,
>>>> it should be sizeof(**fields). This is not causing a problem since
>>>> the size of these is the same. Fix this in the kmalloc_array and
>>>> memcpy calls.
>>> []
>>>> diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
>>> []
>>>> @@ -216,11 +216,11 @@ int template_desc_init_fields(const char *template_fmt,
>>>>  	}
>>>>  
>>>>  	if (fields && num_fields) {
>>>> -		*fields = kmalloc_array(i, sizeof(*fields), GFP_KERNEL);
>>>> +		*fields = kmalloc_array(i, sizeof(**fields), GFP_KERNEL);
>>>>  		if (*fields = NULL)
>>>>  			return -ENOMEM;
>>>>  
>>>> -		memcpy(*fields, found_fields, i * sizeof(*fields));
>>>> +		memcpy(*fields, found_fields, i * sizeof(**fields));
>>>
>>> Maybe use kmemdup instead.
>>>
>>> 	if (fields && num_fields) {
>>> 		*fields = kmemdup(found_fields, i * sizeof(**fields), GFP_KERNEL);
>>> 		etc...
>>>
>>
>> Thanks, Joe.  Since this patch will be backported, perhaps it would be
>> better to leave this as a bug fix and upstream other changes
>> independently.
> 
> IMO:
> 
> This patch doesn't need need backporting as it doesn't
> actually fix anything other than a style defect.
> 
> void * and void ** are the same size.

indeed, same size, it's a semantic difference *and* a style fix :-)

Colin

> 
> cheers, Joe
>