linux-kernel - Re: [PATCH v4 1/3] mm/slab: Use memzero

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <879079.1592322400@warthog.procyon.org.uk>
Date:   Tue, 16 Jun 2020 16:46:40 +0100
From:   David Howells <dhowells@...hat.com>
To:     Waiman Long <longman@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, ebiggers@...nel.org,
        David Howells <dhowells@...hat.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Joe Perches <joe@...ches.com>,
        Matthew Wilcox <willy@...radead.org>,
        David Rientjes <rientjes@...gle.com>,
        Michal Hocko <mhocko@...e.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        David Sterba <dsterba@...e.cz>,
        "Jason A . Donenfeld" <Jason@...c4.com>, linux-mm@...ck.org,
        keyrings@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-amlogic@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-ppp@...r.kernel.org, wireguard@...ts.zx2c4.com,
        linux-wireless@...r.kernel.org, devel@...verdev.osuosl.org,
        linux-scsi@...r.kernel.org, target-devel@...r.kernel.org,
        linux-btrfs@...r.kernel.org, linux-cifs@...r.kernel.org,
        linux-fscrypt@...r.kernel.org, ecryptfs@...r.kernel.org,
        kasan-dev@...glegroups.com, linux-bluetooth@...r.kernel.org,
        linux-wpan@...r.kernel.org, linux-sctp@...r.kernel.org,
        linux-nfs@...r.kernel.org, tipc-discussion@...ts.sourceforge.net,
        linux-security-module@...r.kernel.org,
        linux-integrity@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v4 1/3] mm/slab: Use memzero_explicit() in kzfree()

Waiman Long <longman@...hat.com> wrote:

> The kzfree() function is normally used to clear some sensitive
> information, like encryption keys, in the buffer before freeing it back
> to the pool. Memset()

"memset()" is all lowercase.

> is currently used for buffer clearing. However unlikely, there is still a
> non-zero probability

I'd say "a possibility".

> that

and I'd move "in [the] future" here.

> the compiler may choose to optimize away the
> memory clearing especially if LTO is being used in the future. To make sure
> that this optimization will never happen

"in these cases"

> , memzero_explicit(), which is introduced in v3.18, is now used in

"instead of"?

> kzfree() to future-proof it.

Davod