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Date:   Fri, 26 Jan 2018 17:35:04 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Andrea Arcangeli <aarcange@redhat.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        LKML <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linuxfoundation.org>,
        Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Borislav Petkov <bp@alien8.de>,
        David Woodhouse <dwmw@amazon.co.uk>,
        Dave Hansen <dave.hansen@intel.com>,
        Will Deacon <will.deacon@arm.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Waiman Long <longman@redhat.com>
Subject: Re: [patch V2 1/2] sysfs/cpu: Add vulnerability folder
Message-ID: <20180126163504.GA19313@kroah.com>
References: <20180107214759.387300853@linutronix.de>
 <20180107214913.096657732@linutronix.de>
 <20180126162331.GB5230@redhat.com>
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On Fri, Jan 26, 2018 at 05:23:31PM +0100, Andrea Arcangeli wrote:
> Hello,
> 
> On Sun, Jan 07, 2018 at 10:48:00PM +0100, Thomas Gleixner wrote:
> > +static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
> > +static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
> > +static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
> 
> This sysfs feature implemented as above is weakening kernel security,
> it should be 0400 above.

See the patch from Jason A. Donenfeld <Jason@zx2c4.com> to do just that:
	Subject: [PATCH] cpu: do not leak vulnerabilities to unprivileged users
	Message-Id: <20180125120401.30596-1-Jason@zx2c4.com>

I'll be queueing it up for 4.16-rc1 and backport it everywhere.

thanks,

greg k-h