linux-kernel - Re: [PATCH] x86/mm/init_32: Don't print out kernel memory layout if KASLR

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Message-ID: <202003021038.8F0369D907@keescook>
Date:   Mon, 2 Mar 2020 10:38:51 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Arvind Sankar <nivedita@...m.mit.edu>
Cc:     dave.hansen@...ux.intel.com, kernel-hardening@...ts.openwall.com,
        linux-kernel@...r.kernel.org, luto@...nel.org, me@...in.cc,
        peterz@...radead.org, tycho@...ho.ws, x86@...nel.org
Subject: Re: [PATCH] x86/mm/init_32: Don't print out kernel memory layout if
 KASLR

On Sat, Feb 29, 2020 at 07:11:23PM -0500, Arvind Sankar wrote:
> On Sat, Feb 29, 2020 at 03:51:45PM -0800, Kees Cook wrote:
> > Arvind Sankar said:
> > > For security, only show the virtual kernel memory layout if KASLR is
> > > disabled.
> > 
> > These have been entirely removed on other architectures, so let's
> > just do the same for ia32 and remove it unconditionally.
> > 
> > 071929dbdd86 ("arm64: Stop printing the virtual memory layout")
> > 1c31d4e96b8c ("ARM: 8820/1: mm: Stop printing the virtual memory layout")
> > 31833332f798 ("m68k/mm: Stop printing the virtual memory layout")
> > fd8d0ca25631 ("parisc: Hide virtual kernel memory layout")
> > adb1fe9ae2ee ("mm/page_alloc: Remove kernel address exposure in free_reserved_area()")
> > 
> > -Kees
> > 
> > -- 
> > Kees Cook
> 
> microblaze (arch/microblaze/mm/init.c) and PPC32 (arch/powerpc/mm/mem.c)
> appear to still print it out. I can't test those, but will resubmit
> x86-32 with it removed.

Might as well fix those up too. :)

-- 
Kees Cook