linux-kernel - Re: [PATCHv2] lkdtm: Add READ_AFTER

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Message-ID: <CAGXu5jL8xBHUkZP8_MZk84Zr5efEUGL8z-o0u5_4ybX4CrAmPQ@mail.gmail.com>
Date:	Tue, 23 Feb 2016 14:37:58 -0800
From:	Kees Cook <keescook@...omium.org>
To:	Laura Abbott <labbott@...hat.com>
Cc:	Laura Abbott <labbott@...oraproject.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Arnd Bergmann <arnd@...db.de>,
	"kernel-hardening@...ts.openwall.com" 
	<kernel-hardening@...ts.openwall.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv2] lkdtm: Add READ_AFTER_FREE test

On Tue, Feb 23, 2016 at 1:25 PM, Kees Cook <keescook@...omium.org> wrote:

> zero poison only:
> DEBUG_PAGEALLOC=n
> PAGE_POISONING=y
> PAGE_POISONING_NO_SANITY=y
> PAGE_POISONING_ZERO=y
> page_poison=on

This combo (in next-20160223) results in an unusable system. :(

[    1.754183] random: init urandom read with 11 bits of entropy available
[    1.768449] hostname (1171) used greatest stack depth: 11808 bytes left
[    1.787954] BUG: Bad page map in process init  pte:3d656c6f736e6f63
pmd:00020067
[    1.789177] addr:00007f9f68200000 vm_flags:00000070 anon_vma:
   (null) mapping:ffff88007c314058 index:141
[    1.790564] file:libdl-2.19.so fault:ext4_filemap_fault
mmap:ext4_file_mmap readpage:ext4_readpage

-Kees

-- 
Kees Cook
Chrome OS & Brillo Security