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;
Date:   Wed, 27 Jun 2018 15:12:48 +0200
From:   Michal Hocko <mhocko@kernel.org>
To:     Richard Weinberger <richard.weinberger@gmail.com>
Cc:     Jefferson Carpenter <jeffersoncarpenter2@gmail.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Memory zeroed when made available to user process
Message-ID: <20180627131248.GA3032@dhcp22.suse.cz>
References: <71d13d76-4591-9206-ebbb-5e9599f10c7c@gmail.com>
 <CAFLxGvyJsjWum34Q67UP+EGkg9+W0nPsMpu8mS9PaH8wL3Rd9g@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAFLxGvyJsjWum34Q67UP+EGkg9+W0nPsMpu8mS9PaH8wL3Rd9g@mail.gmail.com>
User-Agent: Mutt/1.10.0 (2018-05-17)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed 27-06-18 13:29:05, Richard Weinberger wrote:
> On Wed, Jun 27, 2018 at 11:34 AM, Jefferson Carpenter
> <jeffersoncarpenter2@gmail.com> wrote:
> > Is there a way for a user process to mark memory as 'sensitive' or
> > 'non-sensitive' when it is allocated?  That could allow it not to have to be
> > zeroed before being allocated to another process.
> 
> Isn't this what we have Meltdown and Spectre for? ;-)
> 
> No, memory from the kernel is always zeroed.
> libc offers malloc() and calloc() for this purpose.

Well, except for the weird MAP_UNINITIALIZED. Anyway agreed that this is
a bad idea and the flag should have never been merged. I've just
mentioned it for completness.

-- 
Michal Hocko
SUSE Labs