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KVM: x86: Add memory barrier on vmcs field lookup

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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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andrew Honig 2018-01-10 10:12:03 -08:00 committed by Greg Kroah-Hartman
parent 431fd501aa
commit 012df71d29
1 changed files with 10 additions and 2 deletions
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12
arch/x86/kvm/vmx.c
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@ -857,8 +857,16 @@ static inline short vmcs_field_to_offset(unsigned long field)
{
BUILD_BUG_ON(ARRAY_SIZE(vmcs_field_to_offset_table) > SHRT_MAX);
if (field >= ARRAY_SIZE(vmcs_field_to_offset_table) ||
vmcs_field_to_offset_table[field] == 0)
if (field >= ARRAY_SIZE(vmcs_field_to_offset_table))
return -ENOENT;
/*
* FIXME: Mitigation for CVE-2017-5753. To be replaced with a
* generic mechanism.
*/
asm("lfence");
if (vmcs_field_to_offset_table[field] == 0)
return -ENOENT;
return vmcs_field_to_offset_table[field];