Re: [PATCH v7 12/18] x86/fsgsbase/64: GSBASE handling with FSGSBASE in the paranoid path

From: Thomas Gleixner
Date: Sat Jun 29 2019 - 03:37:51 EST


On Sat, 29 Jun 2019, Bae, Chang Seok wrote:
> > On May 8, 2019, at 03:02, Chang S. Bae <chang.seok.bae@xxxxxxxxx> wrote:
> >
> > ENTRY(paranoid_exit)
> > â
> > +
> > + /* On FSGSBASE systems, always restore the stashed GSBASE */
> > + wrgsbase %rbx
> > + jmp .Lparanoid_exit_no_swapgs;
>
> It would crash any time getting a paranoid entry with user GS but kernel CR3.
> The issue is thankfully uncovered by Vegard N. A relevant test case will be
> published by Andy L. The patch fixes the issue. (Rebased on the tip master.)

Can you please provide a proper patch with a proper changelog?

Thanks,

tglx