linux-kernel - Re: [PATCH v2] mm: Add kvfree_sensitive() for freeing sensitive data objects

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Message-ID: <20200406200016.GJ21484@bombadil.infradead.org>
Date:   Mon, 6 Apr 2020 13:00:16 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     Waiman Long <longman@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        David Howells <dhowells@...hat.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>, linux-mm@...ck.org,
        keyrings@...r.kernel.org, linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Joe Perches <joe@...ches.com>,
        David Rientjes <rientjes@...gle.com>
Subject: Re: [PATCH v2] mm: Add kvfree_sensitive() for freeing sensitive data
 objects

On Mon, Apr 06, 2020 at 02:58:27PM -0400, Waiman Long wrote:
> +/**
> + * kvfree_sensitive - free a data object containing sensitive information
> + * @addr - address of the data object to be freed
> + * @len  - length of the data object

Did you try building this with W=1?  I believe this is incorrect kerneldoc.
It should be @addr: and @len:

Also, it reads better in the htmldocs if you capitalise the first letter
of each sentence and finish with a full stop.

> @@ -914,7 +911,7 @@ long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
>  		 */
>  		if (ret > key_data_len) {
>  			if (unlikely(key_data))
> -				__kvzfree(key_data, key_data_len);
> +				kvfree_sensitive(key_data, key_data_len);

I'd drop the test of key_data here.