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authorAndrew Honig <ahonig@google.com>2018-01-10 21:12:03 +0300
committerBen Hutchings <ben@decadent.org.uk>2018-03-03 18:50:58 +0300
commit39a34000fbdf7b64db95112686658662fd723841 (patch)
tree988792b455117f0ef8b18cc1be00635634a95ee7 /arch/x86/kvm
parentccaa16ab073a8e0b94ce1d32d9da1199adf712df (diff)
downloadlinux-39a34000fbdf7b64db95112686658662fd723841.tar.xz
KVM: x86: Add memory barrier on vmcs field lookup
commit 75f139aaf896d6fdeec2e468ddfa4b2fe469bf40 upstream. This adds a memory barrier when performing a lookup into the vmcs_field_to_offset_table. This is related to CVE-2017-5753. Signed-off-by: Andrew Honig <ahonig@google.com> Reviewed-by: Jim Mattson <jmattson@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'arch/x86/kvm')
-rw-r--r--arch/x86/kvm/vmx.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 346fac6eab9f..690120f552db 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -573,8 +573,18 @@ static const int max_vmcs_field = ARRAY_SIZE(vmcs_field_to_offset_table);
static inline short vmcs_field_to_offset(unsigned long field)
{
- if (field >= max_vmcs_field || vmcs_field_to_offset_table[field] == 0)
+ if (field >= max_vmcs_field)
return -1;
+
+ /*
+ * FIXME: Mitigation for CVE-2017-5753. To be replaced with a
+ * generic mechanism.
+ */
+ asm("lfence");
+
+ if (vmcs_field_to_offset_table[field] == 0)
+ return -1;
+
return vmcs_field_to_offset_table[field];
}