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

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Date:   Mon, 12 Oct 2020 11:06:04 -0700
From:   Joe Perches <joe@...ches.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>,
        Colin King <colin.king@...onical.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 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.

cheers, Joe