From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Kees Cook <kees.cook@canonical.com>,
Jeremy Fitzhardinge <jeremy@goop.org>,
keir.fraser@eu.citrix.com, castet.matthieu@free.fr
Cc: mingo@redhat.com, hpa@zytor.com, sliakh.lkml@gmail.com,
jmorris@namei.org, linux-kernel@vger.kernel.org,
rusty@rustcorp.com.au, torvalds@linux-foundation.org, ak@muc.de,
davej@redhat.com, jiang@cs.ncsu.edu, arjan@infradead.org,
tglx@linutronix.de, sfr@canb.auug.org.au, mingo@elte.hu,
Stefan Bader <stefan.bader@canonical.com>
Subject: Re: [tip:x86/security] x86: Add NX protection for kernel data
Date: Wed, 19 Jan 2011 16:14:32 -0500 [thread overview]
Message-ID: <20110119211432.GA20535@dumpdata.com> (raw)
In-Reply-To: <20110114201530.GA14339@dumpdata.com>
On Fri, Jan 14, 2011 at 03:15:30PM -0500, Konrad Rzeszutek Wilk wrote:
> On Tue, Jan 11, 2011 at 03:31:35PM -0800, Kees Cook wrote:
> > On Thu, Nov 18, 2010 at 02:08:22PM +0000, tip-bot for Matthieu Castet wrote:
> > > Commit-ID: 5bd5a452662bc37c54fb6828db1a3faf87e6511c
> > > Gitweb: http://git.kernel.org/tip/5bd5a452662bc37c54fb6828db1a3faf87e6511c
> > > Author: Matthieu Castet <castet.matthieu@free.fr>
> > > AuthorDate: Tue, 16 Nov 2010 22:31:26 +0100
> > > Committer: Ingo Molnar <mingo@elte.hu>
> > > CommitDate: Thu, 18 Nov 2010 12:52:04 +0100
> > >
> > > x86: Add NX protection for kernel data
> >
> > [I'd sent this in reply to the wrong patch before, resending now...]
> >
> > Hi,
> >
> > I was just shown this[1] on Xen from an Ubuntu bug report[2].
> >
> > [ 1.230382] NX-protecting the kernel data: 3884k
> > [ 1.231002] BUG: unable to handle kernel paging request at c1782ae0
> > ...
> > [ 1.231145] Call Trace:
> > [ 1.231152] [<c0138481>] ? __change_page_attr+0x2c1/0x370
> > [ 1.231161] [<c02163a1>] ? __purge_vmap_area_lazy+0xc1/0x180
> > [ 1.231169] [<c013857c>] ? __change_page_attr_set_clr+0x4c/0xb0
> > [ 1.231176] [<c0138838>] ? change_page_attr_set_clr+0x128/0x300
> > [ 1.231183] [<c010798e>] ? __raw_callee_save_xen_restore_fl+0x6/0x8
> > [ 1.231192] [<c0159ca1>] ? vprintk+0x171/0x3f0
> > [ 1.231198] [<c0138bdf>] ? set_memory_nx+0x5f/0x70
>
> If you run it with Xen debugging enabled:
>
> [ 7.753329] NX-protecting the kernel data: 2400k
> (XEN) mm.c:2389:d0 Bad type (saw 3c000003 != exp 70000000) for mfn 1355a5 (pfn 15a5)
> (XEN) mm.c:889:d0 Error getting mfn 1355a5 (pfn 15a5) from L1 entry 80000001355a5063 for l1e_owner=0, pg_owner=0
> (XEN) mm.c:4958:d0 ptwr_emulate: could not get_page_from_l1e()
> [ 7.759087] BUG: unable to handle kernel paging request at c82a4d28
> [ 7.759087] IP: [<c100608c>] xen_set_pte_atomic+0x21/0x2f
> [ 7.759087] *pdpt = 0000000001663001 *pde = 00000000082db067 *pte = 80000000082a4061
> .. and same stack trace.
>
> >
> >
> > Does Xen have different size page table allocations or something weird?
>
> The same page size. Not sure actually why it is being triggered. Let me copy
> Keir on this. Keir, the region that is being marked as _NX is .bss one and
Um, it actually is from _etext -> __init_end + HPAGE_SIZE.
instrumenting the code a bit shows that setting of RW+NX from _etext throgh
__init_end works just fine. It just when you start at the PFN _past_ the
__init_end it dies. Any ideas?
next prev parent reply other threads:[~2011-01-19 21:18 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-16 21:31 [PATCH 2/3 V8] NX protection for kernel data matthieu castet
2010-11-18 14:08 ` [tip:x86/security] x86: Add " tip-bot for Matthieu Castet
2011-01-11 23:31 ` Kees Cook
2011-01-14 20:15 ` Konrad Rzeszutek Wilk
2011-01-19 21:14 ` Konrad Rzeszutek Wilk [this message]
2011-01-19 22:59 ` matthieu castet
2011-01-19 23:38 ` Konrad Rzeszutek Wilk
2011-01-20 11:18 ` castet.matthieu
2011-01-20 15:06 ` Konrad Rzeszutek Wilk
2011-01-20 15:37 ` Ian Campbell
2011-01-20 19:05 ` Konrad Rzeszutek Wilk
2011-01-20 20:23 ` matthieu castet
2011-01-20 21:04 ` Konrad Rzeszutek Wilk
2011-01-20 21:19 ` Konrad Rzeszutek Wilk
2011-01-20 21:55 ` Konrad Rzeszutek Wilk
2011-01-21 21:41 ` matthieu castet
2011-01-22 5:11 ` Konrad Rzeszutek Wilk
2011-01-23 14:27 ` matthieu castet
2011-01-24 15:31 ` Konrad Rzeszutek Wilk
2011-01-27 16:30 ` Was: [tip:x86/security] x86: Add NX protection for kernel data. Is: don't set RW on RO regions in .bss Konrad Rzeszutek Wilk
2011-01-21 23:20 ` [tip:x86/security] x86: Add NX protection for kernel data Konrad Rzeszutek Wilk
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