linux-kernel - Re: [PATCH] ima: Fix sizeof mismatches

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Message-ID: <ba5f4d90c714eba5d5a1d822bca25305b40a73e1.camel@linux.ibm.com>
Date:   Tue, 13 Oct 2020 12:17:37 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Colin Ian King <colin.king@...onical.com>,
        Joe Perches <joe@...ches.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E . Hallyn" <serge@...lyn.com>,
        Roberto Sassu <roberto.sassu@...ito.it>,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ima: Fix sizeof mismatches

On Mon, 2020-10-12 at 19:10 +0100, Colin Ian King wrote:
> 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, based on Joe's suggestion of using kmemdup and his opinion of
not backporting this change, can I assume you'll address his comments
and re-post v3?

thanks,

Mimi