lkml.org 
[lkml]   [2020]   [Nov]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: How should we handle illegal task FPU state?
    On Thu, Oct 01, 2020 at 03:04:48PM -0700, Andy Lutomirski wrote:
    > On Thu, Oct 1, 2020 at 2:50 PM Dave Hansen <dave.hansen@intel.com> wrote:
    > > I'm not sure we should ever keep running userspace after an XRSTOR*
    > > failure. For MPX, this might have provided a nice, additional vector
    > > for an attacker to turn off MPX. Same for pkeys if we didn't correctly
    > > differentiate between the hardware init state versus the "software init"
    > > state that we keep in init_task.
    > >
    > > What's the advantage of letting userspace keep running after we init its
    > > state? That it _might_ be able to recover?
    >
    > I suppose we can kill userspace and change that behavior only if
    > someone complains. I still think it would be polite to try to dump
    > core, but that could be tricky with the current code structure. I'll
    > try to whip up a patch. Maybe I'll add a debugfs file to trash MXCSR
    > for testing.

    Just for the record, I like this: safe and simple. We can always do
    smarter shenanigans later, if at all needed, that is.

    --
    Regards/Gruss,
    Boris.

    https://people.kernel.org/tglx/notes-about-netiquette

    \
     
     \ /
      Last update: 2020-11-02 19:40    [W:2.596 / U:0.632 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site