linux-kernel - Re: [PATCH 06/18] x86, barrier: stop speculation for failed access

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Message-ID: <alpine.DEB.2.20.1801071107001.2606@nanos>
Date:   Sun, 7 Jan 2018 11:08:24 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
cc:     Alan Cox <gnomes@...rguk.ukuu.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Dan Williams <dan.j.williams@...el.com>,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        Andi Kleen <ak@...ux.intel.com>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Zijlstra <peterz@...radead.org>, netdev@...r.kernel.org,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH 06/18] x86, barrier: stop speculation for failed
 access_ok

On Sat, 6 Jan 2018, Alexei Starovoitov wrote:
> which clearly states that bpf_tail_call() was used in the attack.
> Yet none of the intel nor arm patches address speculation in
> this bpf helper!
> It means that:
> - gpz didn't share neither exploit nor the detailed description
>   of the POC with cpu vendors until now
> - coverity rules used to find all these places in the kernel
>   failed to find bpf_tail_call
> - cpu vendors were speculating what variant 1 can actually do

You forgot to mention that there might be other attacks than the public POC
which are not covered by a simple AND ....

Thanks,

	tglx