linux-kernel - Re: [PATCH v2 0/8] x86/kaslr: Cleanup and small bugfixes

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Message-ID: <20200728142442.GA3869481@rani.riverdale.lan>
Date:   Tue, 28 Jul 2020 10:24:42 -0400
From:   Arvind Sankar <nivedita@...m.mit.edu>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Arvind Sankar <nivedita@...m.mit.edu>,
        Kees Cook <keescook@...omium.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/8] x86/kaslr: Cleanup and small bugfixes

On Tue, Jul 28, 2020 at 01:06:17PM +0200, Ingo Molnar wrote:
> 
> * Arvind Sankar <nivedita@...m.mit.edu> wrote:
> 
> > The first 7 patches are cleanup and minor bugfixes on the x86 KASLR
> > code.
> > 
> > The last one is a bit of an RFC. The memory regions used for KASLR are
> > stored as 64-bit even on a 32-bit kernel. However there are still a few
> > local variables that are 32-bit, but should be ok as far as I can see
> > because they are assigned values that have been already limited to
> > 32-bit. It does make it a little harder to verify that the code is
> > correct. Since KASLR cannot actually use 64-bit regions for the 32-bit
> > kernel, the patch reduces regions to their below-4G segment when
> > creating them, making the actual variables 32-bit. Alternatively, the
> > few local variables could be upgraded to 64-bit.
> > 
> > v1->v2:
> > - Fix a bug in the bugfix 5/8: overlap.start can be smaller than
> >   region.start, so shouldn't subtract before comparing.
> > 
> > Arvind Sankar (8):
> >   x86/kaslr: Make command line handling safer
> >   x86/kaslr: Remove bogus warning and unnecessary goto
> >   x86/kaslr: Fix process_efi_entries comment
> >   x86/kaslr: Initialize mem_limit to the real maximum address
> >   x86/kaslr: Simplify __process_mem_region
> >   x86/kaslr: Simplify process_gb_huge_pages
> >   x86/kaslr: Clean up slot handling
> >   x86/kaslr: Don't use 64-bit mem_vector for 32-bit kernel
> > 
> >  arch/x86/boot/compressed/acpi.c  |   7 +-
> >  arch/x86/boot/compressed/kaslr.c | 228 ++++++++++++-------------------
> >  arch/x86/boot/compressed/misc.h  |  19 ++-
> >  3 files changed, 111 insertions(+), 143 deletions(-)
> 
> I've applied patches 1-4 to x86/kaslr and will push them out if they 
> pass testing - see the review feedback for the others.
> 
> Thanks,
> 
> 	Ingo

Ok, thanks, I will send them split out and replace the last patch.