linux-kernel - Re: [PATCH 2/9] thunderbolt: show key using %*s not %*pE

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Date:   Thu, 5 Sep 2019 14:17:10 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "J. Bruce Fields" <bfields@...hat.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/9] thunderbolt: show key using %*s not %*pE

On Thu, Sep 05, 2019 at 03:44:26PM -0400, J. Bruce Fields wrote:
> From: "J. Bruce Fields" <bfields@...hat.com>
> 
> %*pEp (without "h" or "o") is a no-op.  This string could contain
> arbitrary (non-NULL) characters, so we do want escaping.  Use %*pE like
> every other caller.

Agreed on all counts. pEp is actively resulting in NO escaping, which is
a bug here.

Acked-by: Kees Cook <keescook@...omium.org>

-Kees

> 
> Signed-off-by: J. Bruce Fields <bfields@...hat.com>
> ---
>  drivers/thunderbolt/xdomain.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/thunderbolt/xdomain.c b/drivers/thunderbolt/xdomain.c
> index 5118d46702d5..4e17a7c7bf0a 100644
> --- a/drivers/thunderbolt/xdomain.c
> +++ b/drivers/thunderbolt/xdomain.c
> @@ -636,7 +636,7 @@ static ssize_t key_show(struct device *dev, struct device_attribute *attr,
>  	 * It should be null terminated but anything else is pretty much
>  	 * allowed.
>  	 */
> -	return sprintf(buf, "%*pEp\n", (int)strlen(svc->key), svc->key);
> +	return sprintf(buf, "%*pE\n", (int)strlen(svc->key), svc->key);
>  }
>  static DEVICE_ATTR_RO(key);
>  
> -- 
> 2.21.0
> 

-- 
Kees Cook