Messages in this thread |  | | | Date | Wed, 19 Jan 2011 23:59:57 +0100 | | From | matthieu castet <> | | Subject | Re: [tip:x86/security] x86: Add NX protection for kernel data |
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Le Wed, 19 Jan 2011 16:14:32 -0500, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> a écrit :
> 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 this happen if (x & (PGT_type_mask|PGT_pae_xen_l2)) != type)
but #define PGT_type_mask (7U<<29) /* Bits 29-31. */ #define _PGT_pae_xen_l2 26 #define PGT_pae_xen_l2 (1U<<_PGT_pae_xen_l2) but (exp type = 0x70000000) & (PGT_type_mask|PGT_pae_xen_l2) = 0x60000000 So the exp type look strange. #define _PGT_pinned 28 #define PGT_pinned (1U<<_PGT_pinned)
> > 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? > Does this happen if you add ". = ALIGN(HPAGE_SIZE);" before bss section in arch/x86/kernel/vmlinux.lds.S ?
Does it happen if you call set_pages_rw instead of set_pages_nx in mark_nxdata_nx ?
What's the output of kernel_page_tables debugfs ?
Matthieu -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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