linux-kernel - Re: [kernel-hardening] [PATCH v5 03/32] x86/cpa: In populate_pgd, don't set the pgd entry until it's populated

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Message-ID: <8376.1469251283@turing-police.cc.vt.edu>
Date:	Sat, 23 Jul 2016 01:21:23 -0400
From:	Valdis.Kletnieks@...edu
To:	Andy Lutomirski <luto@...nel.org>
Cc:	kernel-hardening@...ts.openwall.com, x86@...nel.org,
	linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
	Borislav Petkov <bp@...en8.de>,
	Nadav Amit <nadav.amit@...il.com>,
	Kees Cook <keescook@...omium.org>,
	Brian Gerst <brgerst@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Josh Poimboeuf <jpoimboe@...hat.com>,
	Jann Horn <jann@...jh.net>,
	Heiko Carstens <heiko.carstens@...ibm.com>
Subject: Re: [kernel-hardening] [PATCH v5 03/32] x86/cpa: In populate_pgd, don't set the pgd entry until it's populated

On Thu, 21 Jul 2016 22:34:33 -0700, Andy Lutomirski said:

> How much memory do you have and what's your config?  My code is
> obviously buggy, but I'm wondering why neither I nor the 0day bot caught
> this.

Probably because your devel box and the 0day bot both have 4-level page
tables and the dual-core i5 in my laptop has (presumably) 3?

In any case, your patch didn't fix things, nor did (as you noted in a mail
to Ingo) does reverting the problem commit (and then the following one that
deletes now-dead code so it will compile cleanly).

8G of memory, 2 4G dimms.  .config attached.  Anything that would help
from /proc or /sys?

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