From: Marios Pomonis <pomonis@xxxxxxxxxx>
[ Upstream commit 4bf79cb089f6b1c6c632492c0271054ce52ad766 ]
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>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/x86/kvm/lapic.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 3c70f6c76d3a2..ce8c4ae25c157 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -36,6 +36,7 @@
#include <asm/delay.h>
#include <linux/atomic.h>
#include <linux/jump_label.h>
+#include <linux/nospec.h>
#include "kvm_cache_regs.h"
#include "irq.h"
#include "trace.h"
@@ -1432,15 +1433,21 @@ static int apic_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];
apic_set_reg(apic, reg, val);
-
break;
+ }
case APIC_LVTT:
if (!kvm_apic_sw_enabled(apic))
--
2.20.1
