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Message-ID: <803557cc672ef0bcd9565c7d5d78e7053388f5d7.camel@perches.com>
Subject: Re: [PATCH] coccinelle: api: add kzfree script
From:   Joe Perches <joe@perches.com>
To:     efremov@linux.com, Julia Lawall <Julia.Lawall@lip6.fr>,
        Dan Carpenter <dan.carpenter@oracle.com>
Cc:     cocci@systeme.lip6.fr, linux-kernel@vger.kernel.org
Date:   Sun, 14 Jun 2020 13:01:51 -0700
In-Reply-To: <345c783b-a8cf-9dd1-29c6-d32b9b29053f@linux.com>
References: <20200604140805.111613-1-efremov@linux.com>
         <e4981fd76a88e18376c4e634c235501b57d321e7.camel@perches.com>
         <345c783b-a8cf-9dd1-29c6-d32b9b29053f@linux.com>
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On Sun, 2020-06-14 at 22:42 +0300, Denis Efremov wrote:
> On 6/4/20 7:27 PM, Joe Perches wrote:
> > On Thu, 2020-06-04 at 17:08 +0300, Denis Efremov wrote:
> > > Check for memset() with 0 followed by kfree().
> > 
> > Perhaps those uses should be memzero_explicit or kvfree_sensitive.
> > 
> Is it safe to suggest to use kzfree instead of memzero_explicit && kfree?
> Or it would be better to use kvfree_sensitive in this case.
> kzfree uses memset(0) with no barrier_data.
> 
> For example:
> diff -u -p a/drivers/crypto/inside-secure/safexcel_hash.c b/drivers/crypto/inside-secure/safexcel_hash.c
[]
> @@ -1081,8 +1081,7 @@ static int safexcel_hmac_init_pad(struct
>                 }
>  
>                 /* Avoid leaking */
> -               memzero_explicit(keydup, keylen);
> -               kfree(keydup);
> +               kzfree(keydup);

It would be better to use kvfree_sensitive()