linux-kernel - Re: [PATCH 14/18] ipv4: prevent bounds-check bypass via speculative execution

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Message-ID: <20180106122347.7a5c8ee6@alans-desktop>
Date:   Sat, 6 Jan 2018 12:23:47 +0000
From:   Alan Cox <gnomes@...rguk.ukuu.org.uk>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Dan Williams <dan.j.williams@...el.com>,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        netdev@...r.kernel.org, peterz@...radead.org,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>, tglx@...utronix.de,
        torvalds@...ux-foundation.org,
        "David S. Miller" <davem@...emloft.net>,
        Elena Reshetova <elena.reshetova@...el.com>,
        alan@...ux.intel.com
Subject: Re: [PATCH 14/18] ipv4: prevent bounds-check bypass via speculative
 execution

On Sat, 6 Jan 2018 10:01:54 +0100
Greg KH <gregkh@...uxfoundation.org> wrote:

> On Fri, Jan 05, 2018 at 05:11:10PM -0800, Dan Williams wrote:
> > Static analysis reports that 'offset' may be a user controlled value  
> 
> Can I see the rule that determined that?  It does not feel like that is
> correct, given the 3+ levels deep that this function gets this value
> from...

On a current x86 you can execute something upwards of 150 instructions in
a speculation window.

Alan