Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <20200407200318.11711-1-longman@redhat.com>
In-Reply-To: <20200407200318.11711-1-longman@redhat.com>
From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Tue, 7 Apr 2020 13:09:11 -0700
Message-ID: <CAHk-=wh4YYef26dFX2o9iAKts6vuPceUNg7Bdq32REnvfOWiog@mail.gmail.com>
Subject: Re: [PATCH v3] mm: Add kvfree_sensitive() for freeing sensitive data objects
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>,
        Linux-MM <linux-mm@kvack.org>, keyrings@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Joe Perches <joe@perches.com>,
        Matthew Wilcox <willy@infradead.org>,
        David Rientjes <rientjes@google.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Apr 7, 2020 at 1:03 PM Waiman Long <longman@redhat.com> wrote:
>
> For kvmalloc'ed data object that contains sensitive information like
> cryptographic key, we need to make sure that the buffer is always
> cleared before freeing it. Using memset() alone for buffer clearing may
> not provide certainty as the compiler may compile it away. To be sure,
> the special memzero_explicit() has to be used.

Ack. Since this isn't exactly high-priority, I'm assuming it will go
through the usual channels (ie Andrew).

             Linus