49 lines
1.5 KiB
Diff
49 lines
1.5 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Andrew Honig <ahonig@google.com>
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Date: Wed, 10 Jan 2018 10:12:03 -0800
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Subject: [PATCH] KVM: x86: Add memory barrier on vmcs field lookup
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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commit 75f139aaf896d6fdeec2e468ddfa4b2fe469bf40 upstream.
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This adds a memory barrier when performing a lookup into
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the vmcs_field_to_offset_table. This is related to
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CVE-2017-5753.
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Signed-off-by: Andrew Honig <ahonig@google.com>
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Reviewed-by: Jim Mattson <jmattson@google.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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arch/x86/kvm/vmx.c | 12 ++++++++++--
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1 file changed, 10 insertions(+), 2 deletions(-)
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diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
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index d2168203bddc..e6fa3df81fd8 100644
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--- a/arch/x86/kvm/vmx.c
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+++ b/arch/x86/kvm/vmx.c
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@@ -882,8 +882,16 @@ static inline short vmcs_field_to_offset(unsigned long field)
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{
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BUILD_BUG_ON(ARRAY_SIZE(vmcs_field_to_offset_table) > SHRT_MAX);
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- if (field >= ARRAY_SIZE(vmcs_field_to_offset_table) ||
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- vmcs_field_to_offset_table[field] == 0)
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+ if (field >= ARRAY_SIZE(vmcs_field_to_offset_table))
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+ return -ENOENT;
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+
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+ /*
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+ * FIXME: Mitigation for CVE-2017-5753. To be replaced with a
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+ * generic mechanism.
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+ */
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+ asm("lfence");
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+
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+ if (vmcs_field_to_offset_table[field] == 0)
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return -ENOENT;
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return vmcs_field_to_offset_table[field];
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--
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2.14.2
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