Re: [tip:x86/kaslr] x86, relocs: Add more per-cpu gold special cases

[Ingo Molnar]

* Kees Cook <keescook@xxxxxxxxxxxx> wrote:

> On Mon, Oct 14, 2013 at 11:04 PM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> >
> > * Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> >
> >> On Mon, Oct 14, 2013 at 9:28 AM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> >> > On 10/14/2013 07:19 AM, H. Peter Anvin wrote:
> >> >> My guess is that the 95 addresses are randomized and the 82 address is an address which failed to relocate.
> >> >
> >> >> ffffffff82a04a58 is:
> >> >> ffffffff82a03000 t init_per_cpu__gdt_page
> >> >
> >> >
> >> > Specifically, it looks like the percpu stuff isn't getting set up correctly.
> >>
> >> It wouldn't surprise me if there are even more percpu things to fix.
> >> It's the main area we've continued to trip over while working on this
> >> with various linkers. Which linker and version are you seeing this
> >> with?
> >
> > The failure I saw triggered with fairly modern userspace:
> >
> >  GNU ld version 2.23.52.0.1-9.fc19 20130226
> >
> >  gcc version 4.8.1 20130603 (Red Hat 4.8.1-1) (GCC)
> 
> Can you try with the gold linker?  When not using Gold, I can produce a 
> similar crash with GNU ld ver 2.23.2 but not 2.22.

I'm not set up for Gold - but maybe others can try your experiment.

If you can see/reproduce the 2.23 crash then maybe that fix will work for 
my testcase as well.

Thanks,

	Ingo
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