The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 4bf79cb089f6b1c6c632492c0271054ce52ad766 Mon Sep 17 00:00:00 2001
From: Marios Pomonis <pomonis@xxxxxxxxxx>
Date: Wed, 11 Dec 2019 12:47:46 -0800
Subject: [PATCH] KVM: x86: Protect kvm_lapic_reg_write() from Spectre-v1/L1TF
attacks
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@xxxxxxxxxx>
Signed-off-by: Marios Pomonis <pomonis@xxxxxxxxxx>
Reviewed-by: Andrew Honig <ahonig@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 88c3c0c6d1e3..865edce27a6a 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1960,15 +1960,20 @@ 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))
