linux-kernel - Re: [PATCH] security: keys: Use kvfree

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Message-ID: <f97076d2-de8a-4600-ee81-4cf4fcdc3ec1@linux.com>
Date:   Fri, 11 Sep 2020 19:05:16 +0300
From:   Denis Efremov <efremov@...ux.com>
To:     Alex Dewar <alex.dewar90@...il.com>
Cc:     David Howells <dhowells@...hat.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>, keyrings@...r.kernel.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] security: keys: Use kvfree_sensitive in a few places

Hi,

same patch

https://lkml.org/lkml/2020/8/27/168

Thanks,
Denis

On 9/11/20 2:44 PM, Alex Dewar wrote:
> In big_key.c, there are a few places where memzero_explicit + kvfree is
> used. It is better to use kvfree_sensitive instead, which is more
> readable and also prevents the compiler from eliding the call to
> memzero_explicit. Fix this.
> 
> Signed-off-by: Alex Dewar <alex.dewar90@...il.com>
> ---
>  security/keys/big_key.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/security/keys/big_key.c b/security/keys/big_key.c
> index 691347dea3c1..d17e5f09eeb8 100644
> --- a/security/keys/big_key.c
> +++ b/security/keys/big_key.c
> @@ -121,8 +121,7 @@ int big_key_preparse(struct key_preparsed_payload *prep)
>  		*path = file->f_path;
>  		path_get(path);
>  		fput(file);
> -		memzero_explicit(buf, enclen);
> -		kvfree(buf);
> +		kvfree_sensitive(buf, enclen);
>  	} else {
>  		/* Just store the data in a buffer */
>  		void *data = kmalloc(datalen, GFP_KERNEL);
> @@ -140,8 +139,7 @@ int big_key_preparse(struct key_preparsed_payload *prep)
>  err_enckey:
>  	kfree_sensitive(enckey);
>  error:
> -	memzero_explicit(buf, enclen);
> -	kvfree(buf);
> +	kvfree_sensitive(buf, enclen);
>  	return ret;
>  }
>  
> @@ -273,8 +271,7 @@ long big_key_read(const struct key *key, char *buffer, size_t buflen)
>  err_fput:
>  		fput(file);
>  error:
> -		memzero_explicit(buf, enclen);
> -		kvfree(buf);
> +		kvfree_sensitive(buf, enclen);
>  	} else {
>  		ret = datalen;
>  		memcpy(buffer, key->payload.data[big_key_data], datalen);
>