linux-kernel - Re: [PATCH v2 2/2] misc: dice: Add driver to forward secrets to userspace

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <YbJnk7elmP4kUZEH@kroah.com>
Date:   Thu, 9 Dec 2021 21:31:15 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Pavel Machek <pavel@....cz>
Cc:     David Brazdil <dbrazdil@...gle.com>,
        Rob Herring <robh+dt@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Derek Kiernan <derek.kiernan@...inx.com>,
        Dragan Cvetic <dragan.cvetic@...inx.com>,
        Arnd Bergmann <arnd@...db.de>,
        Hans de Goede <hdegoede@...hat.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, Andrew Scull <ascull@...gle.com>,
        Will Deacon <will@...nel.org>
Subject: Re: [PATCH v2 2/2] misc: dice: Add driver to forward secrets to
 userspace

On Thu, Dec 09, 2021 at 08:38:57PM +0100, Pavel Machek wrote:
> Hi!
> 
> > > +	memzero_explicit(kaddr, dice_rmem->size);
> > > +	devm_memunmap(dice_misc.this_device, kaddr);
> > 
> > Do you really need to call memzero_explicit()?  This isn't "local"
> > memory, if the compiler "optimizes away" a normal call, it would be
> > _VERY_ broken.
> 
> For clearing secrets, I believe memzero_explicit is nice
> documentation.

Only if it's really needed please.