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Date: Fri, 6 Mar 2020 09:04:40 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
Cc: Arvind Sankar <nivedita@...m.mit.edu>, Kees Cook <keescook@...omium.org>,
"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 list <linux-sh@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] sh: Stop printing the virtual memory layout
Hi Adrian,
On Thu, Mar 5, 2020 at 4:18 PM John Paul Adrian Glaubitz
<glaubitz@...sik.fu-berlin.de> 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.
In most of the above (but not in this patch), "%p" was used to print
addresses, which started showing useless hashed addresses since commit
ad67b74d2469d9b8 ("printk: hash addresses printed with %p").
Instead of changing them all to print usable addresses instead, it was
agreed upon to just remove them.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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