linux-kernel - Re: [PATCH] sh: Stop printing the virtual memory layout

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Message-ID: <31d1567c4c195f3bc5c6b610386cf0f559f9094f.camel@perches.com>
Date:   Thu, 05 Mar 2020 07:38:01 -0800
From:   Joe Perches <joe@...ches.com>
To:     John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Kees Cook <keescook@...omium.org>
Cc:     "Tobin C . Harding" <me@...in.cc>, Tycho Andersen <tycho@...ho.ws>,
        kernel-hardening@...ts.openwall.com,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>, linux-sh@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sh: Stop printing the virtual memory layout

On Thu, 2020-03-05 at 16:18 +0100, John Paul Adrian Glaubitz wrote:
> On 3/5/20 4:10 PM, Arvind Sankar wrote:
> > For security, don't display the kernel's virtual memory layout.
> > 
> > Kees Cook points out:
> > "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()")
> Aww, why wasn't this made configurable? I found these memory map printouts
> very useful for development.

It could be changed from pr_info to pr_devel.

A #define DEBUG would have to be added to emit it.