lkml.org 
[lkml]   [2018]   [Jan]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [PATCH 06/18] x86, barrier: stop speculation for failed access_ok
    On Tue, Jan 9, 2018 at 2:23 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
    > On Tue, Jan 09, 2018 at 01:59:04PM -0800, Dan Williams wrote:
    >> > Right, but what's the purpose of preventing speculation past
    >> > access_ok()?
    >>
    >> Caution. It's the same rationale for the nospec_array_ptr() patches.
    >> If we, kernel community, can identify any possible speculation past a
    >> bounds check we should inject a speculation mitigation. Unless there's
    >> a way to be 100% certain that the first unwanted speculation can be
    >> turned into a gadget later on in the instruction stream, err on the
    >> side of shutting it down early.
    >
    > I'm all for being cautious. The nospec_array_ptr() patches are fine,
    > and they make sense in light of the variant 1 CVE.
    >
    > But that still doesn't answer my question. I haven't seen *any*
    > rationale for this patch. It would be helpful to at least describe
    > what's being protected against, even if it's hypothetical. How can we
    > review it if the commit log doesn't describe its purpose?

    Certainly the changelog needs improvement, I'll roll these concerns
    into v2 and we can go from there.

    \
     
     \ /
      Last update: 2018-01-14 23:20    [W:4.355 / U:0.064 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site