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From: Michal Hocko <mhocko@kernel.org>
To: Waiman Long <longman@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	David Howells <dhowells@redhat.com>,
	Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Joe Perches <joe@perches.com>,
	Matthew Wilcox <willy@infradead.org>,
	David Rientjes <rientjes@google.com>,
	linux-mm@kvack.org, keyrings@vger.kernel.org,
	linux-kernel@vger.kernel.org, x86@kernel.org,
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Subject: Re: [PATCH 1/2] mm, treewide: Rename kzfree() to kfree_sensitive()
Date: Tue, 14 Apr 2020 11:01:29 +0200
Message-ID: <20200414090129.GE4629@dhcp22.suse.cz> (raw)
In-Reply-To: <20200413211550.8307-2-longman@redhat.com>

On Mon 13-04-20 17:15:49, Waiman Long wrote:
> As said by Linus:
> 
>   A symmetric naming is only helpful if it implies symmetries in use.
>   Otherwise it's actively misleading.
> 
>   In "kzalloc()", the z is meaningful and an important part of what the
>   caller wants.
> 
>   In "kzfree()", the z is actively detrimental, because maybe in the
>   future we really _might_ want to use that "memfill(0xdeadbeef)" or
>   something. The "zero" part of the interface isn't even _relevant_.
> 
> The main reason that kzfree() exists is to clear sensitive information
> that should not be leaked to other future users of the same memory
> objects.
> 
> Rename kzfree() to kfree_sensitive() to follow the example of the
> recently added kvfree_sensitive() and make the intention of the API
> more explicit. In addition, memzero_explicit() is used to clear the
> memory to make sure that it won't get optimized away by the compiler.
> 
> The renaming is done by using the command sequence:
> 
>   git grep -w --name-only kzfree |\
>   xargs sed -i 's/\bkzfree\b/kfree_sensitive/'
> 
> followed by some editing of the kfree_sensitive() kerneldoc and the
> use of memzero_explicit() instead of memset().
> 
> Suggested-by: Joe Perches <joe@perches.com>
> Signed-off-by: Waiman Long <longman@redhat.com>

Makes sense. I haven't checked all the conversions and will rely on the
script doing the right thing. The core MM part is correct.

Acked-by: Michal Hocko <mhocko@suse.com>
-- 
Michal Hocko
SUSE Labs

  parent reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-13 21:15 [PATCH 0/2] " Waiman Long
2020-04-13 21:15 ` [PATCH 1/2] " Waiman Long
2020-04-14  0:29   ` David Rientjes
2020-04-14  8:32   ` Jason A. Donenfeld
2020-04-14  9:01   ` Michal Hocko [this message]
2020-04-14 12:48   ` David Sterba
2020-04-14 18:26     ` Waiman Long
2020-04-15  5:01   ` Johannes Weiner
2020-06-15 18:07   ` Dan Carpenter
2020-06-15 18:39     ` Waiman Long
2020-04-13 21:15 ` [PATCH 2/2] crypto: Remove unnecessary memzero_explicit() Waiman Long
2020-04-13 21:31   ` Joe Perches
2020-04-13 21:52     ` Waiman Long
2020-04-13 22:28 ` [PATCH v2 " Waiman Long
2020-04-14  6:08   ` Christophe Leroy
2020-04-14 16:24     ` Waiman Long
2020-04-14 19:16       ` Michal Suchánek
2020-04-14 19:37         ` Waiman Long
2020-04-14 19:44           ` Joe Perches
2020-04-14 13:06 ` [PATCH 1/2] mm, treewide: Rename kzfree() to kfree_sensitive() David Howells

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