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KVM: x86: Protect kvm_lapic_reg_write() from Spectre-v1/L1TF attacks 

commit 4bf79cb089 upstream.

This fixes a Spectre-v1/L1TF vulnerability in kvm_lapic_reg_write().
This function contains index computations based on the
(attacker-controlled) MSR number.

Fixes: 0105d1a526 ("KVM: x2apic interface to lapic")

Signed-off-by: Nick Finco <nifi@google.com>
Signed-off-by: Marios Pomonis <pomonis@google.com>
Reviewed-by: Andrew Honig <ahonig@google.com>
Cc: stable@vger.kernel.org
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Marios Pomonis 2019-12-11 12:47:46 -08:00 committed by Greg Kroah-Hartman
parent 8b73ccf4b4
commit bf13472e5c
1 changed files with 9 additions and 4 deletions
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13
arch/x86/kvm/lapic.c
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@ -1926,15 +1926,20 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
case APIC_LVTTHMR:
case APIC_LVTPC:
case APIC_LVT1:
case APIC_LVTERR:
case APIC_LVTERR: {
/* TODO: Check vector */
size_t size;
u32 index;
if (!kvm_apic_sw_enabled(apic))
val |= APIC_LVT_MASKED;
val &= apic_lvt_mask[(reg - APIC_LVTT) >> 4];
size = ARRAY_SIZE(apic_lvt_mask);
index = array_index_nospec(
(reg - APIC_LVTT) >> 4, size);
val &= apic_lvt_mask[index];
kvm_lapic_set_reg(apic, reg, val);
break;
}
case APIC_LVTT:
if (!kvm_apic_sw_enabled(apic))