linux-kernel - Re: [RFC PATCH 0/2] x86: Fix missing core serialization on migration

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: <CA+55aFzbroWqi+FTdYhRVSwUZ-M0wDVxjXqDbh40JEnXc2LdgQ@mail.gmail.com>
Date:   Fri, 10 Nov 2017 13:36:57 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Andrew Hunter <ahh@...gle.com>,
        Maged Michael <maged.michael@...il.com>,
        Avi Kivity <avi@...lladb.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Dave Watson <davejwatson@...com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Andrea Parri <parri.andrea@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Greg Hackmann <ghackmann@...gle.com>,
        Will Deacon <will.deacon@....com>,
        David Sehr <sehr@...gle.com>,
        "the arch/x86 maintainers" <x86@...nel.org>
Subject: Re: [RFC PATCH 0/2] x86: Fix missing core serialization on migration

On Fri, Nov 10, 2017 at 1:12 PM, Mathieu Desnoyers
<mathieu.desnoyers@...icios.com> wrote:
> x86 can return to user-space through sysexit and sysretq, which are not
> core serializing. This breaks expectations from user-space about
> sequential consistency from a single-threaded self-modifying program
> point of view in specific migration patterns.
>
> Feedback is welcome,

We should check with Intel. I would actually be surprised if the I$
can be out of sync with the D$ after a sysretq.  It would actually
break things like "read code from disk" too in theory.

Hpa? Can you check?

              Linus