Date: Wed, 24 Feb 2016 10:59:22 -0800 From: Laura Abbott <labbott@...hat.com> To: Kees Cook <keescook@...omium.org> 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 02/23/2016 02:37 PM, Kees Cook wrote: > 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 > Hmmm, it looks like the -mm tree currently only has the v1 of the poisoning patches and not the v2. The v1 had a bug which would cause issues like this due to some pages not getting zeroed fully. I should follow up on that today. Thanks, Laura
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