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768717cce7
Preparatory change in order to import a newer Xen version while keeping the previous one. Reviewed by: bapt Sponsored by: Citrix Systems R&D Differential Revision: https://reviews.freebsd.org/D16416
52 lines
1.5 KiB
Diff
52 lines
1.5 KiB
Diff
From fa7268b94f8a0a7792ee12d5b8e23a60e52a3a84 Mon Sep 17 00:00:00 2001
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From: Andrew Cooper <andrew.cooper3@citrix.com>
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Date: Tue, 20 Jun 2017 19:18:54 +0100
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Subject: [PATCH] x86/grant: Disallow misaligned PTEs
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Pagetable entries must be aligned to function correctly. Disallow attempts
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from the guest to have a grant PTE created at a misaligned address, which
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would result in corruption of the L1 table with largely-guest-controlled
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values.
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This is XSA-227
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Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
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Reviewed-by: Jan Beulich <jbeulich@suse.com>
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---
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xen/arch/x86/mm.c | 13 +++++++++++++
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1 file changed, 13 insertions(+)
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diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
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index 97b3b4b..00f517a 100644
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--- a/xen/arch/x86/mm.c
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+++ b/xen/arch/x86/mm.c
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@@ -3763,6 +3763,9 @@ static int create_grant_pte_mapping(
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l1_pgentry_t ol1e;
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struct domain *d = v->domain;
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+ if ( !IS_ALIGNED(pte_addr, sizeof(nl1e)) )
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+ return GNTST_general_error;
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+
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adjust_guest_l1e(nl1e, d);
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gmfn = pte_addr >> PAGE_SHIFT;
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@@ -3819,6 +3822,16 @@ static int destroy_grant_pte_mapping(
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struct page_info *page;
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l1_pgentry_t ol1e;
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+ /*
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+ * addr comes from Xen's active_entry tracking so isn't guest controlled,
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+ * but it had still better be PTE-aligned.
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+ */
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+ if ( !IS_ALIGNED(addr, sizeof(ol1e)) )
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+ {
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+ ASSERT_UNREACHABLE();
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+ return GNTST_general_error;
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+ }
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+
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gmfn = addr >> PAGE_SHIFT;
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page = get_page_from_gfn(d, gmfn, NULL, P2M_ALLOC);
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--
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2.1.4
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