On Tue, Nov 06, 2018 at 06:11:18PM +, Nadav Amit wrote:
> From: Peter Zijlstra
> > On Tue, Nov 06, 2018 at 09:20:19AM +0100, Peter Zijlstra wrote:
> >
> >> By our current way of thinking, kmap_atomic simply is not correct.
> >
> > Something like the below; which weirdly builds an x86_32 kerne
: Re: [PATCH v3 6/7] x86/alternatives: use temporary mm for text poking
>
>
> On Tue, Nov 06, 2018 at 09:20:19AM +0100, Peter Zijlstra wrote:
>
>> By our current way of thinking, kmap_atomic simply is not correct.
>
> Something like the below; which weirdly builds an x8
On Tue, Nov 06, 2018 at 09:20:19AM +0100, Peter Zijlstra wrote:
> By our current way of thinking, kmap_atomic simply is not correct.
Something like the below; which weirdly builds an x86_32 kernel.
Although I imagine a very sad one.
---
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ba7
Borislav Petkov , Dave Hansen
> > , Andy Lutomirski , Kees Cook
> > , Dave Hansen , Masami
> > Hiramatsu
> > Subject: Re: [PATCH v3 6/7] x86/alternatives: use temporary mm for text
> > poking
> >
> >
> > On Fri, Nov 02, 2018 at 04:29:45PM -0700, Nadav
asami
> Hiramatsu
> Subject: Re: [PATCH v3 6/7] x86/alternatives: use temporary mm for text poking
>
>
> On Fri, Nov 02, 2018 at 04:29:45PM -0700, Nadav Amit wrote:
>> +unuse_temporary_mm(prev);
>> +
>> +pte_unmap_unlock(ptep, ptl);
>
> That; that does k
On Fri, Nov 02, 2018 at 04:29:45PM -0700, Nadav Amit wrote:
> + unuse_temporary_mm(prev);
> +
> + pte_unmap_unlock(ptep, ptl);
That; that does kunmap_atomic() on 32bit.
I've been thinking that the whole kmap_atomic thing on x86_32 is
terminally broken, and with that most of x86_32 is.
km
On Fri, Nov 02, 2018 at 04:29:45PM -0700, Nadav Amit wrote:
> diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
> index 9ceae28db1af..1a40df4db450 100644
> --- a/arch/x86/kernel/alternative.c
> +++ b/arch/x86/kernel/alternative.c
> @@ -699,41 +700,110 @@ __ro_after_init un
text_poke() can potentially compromise the security as it sets temporary
PTEs in the fixmap. These PTEs might be used to rewrite the kernel code
from other cores accidentally or maliciously, if an attacker gains the
ability to write onto kernel memory.
Moreover, since remote TLBs are not flushed a
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