From: Marios Pomonis pomonis@google.com
commit 4bf79cb089f6b1c6c632492c0271054ce52ad766 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: 0105d1a52640 ("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
--- arch/x86/kvm/lapic.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
--- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1926,15 +1926,20 @@ int kvm_lapic_reg_write(struct kvm_lapic 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))