From: Marios Pomonis <pomonis@xxxxxxxxxx>
commit 6ec4c5eee1750d5d17951c4e1960d953376a0dda upstream.
This fixes a Spectre-v1/L1TF vulnerability in set_msr_mce() and
get_msr_mce().
Both functions contain index computations based on the
(attacker-controlled) MSR number.
Fixes: 890ca9aefa78 ("KVM: Add MCE support")
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: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/x86.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1994,7 +1994,10 @@ static int set_msr_mce(struct kvm_vcpu *
default:
if (msr >= MSR_IA32_MC0_CTL &&
msr < MSR_IA32_MCx_CTL(bank_num)) {
- u32 offset = msr - MSR_IA32_MC0_CTL;
+ u32 offset = array_index_nospec(
+ msr - MSR_IA32_MC0_CTL,
+ MSR_IA32_MCx_CTL(bank_num) - MSR_IA32_MC0_CTL);
+
/* only 0 or all 1s can be written to IA32_MCi_CTL
* some Linux kernels though clear bit 10 in bank 4 to
* workaround a BIOS/GART TBL issue on AMD K8s, ignore
@@ -2355,7 +2358,10 @@ static int get_msr_mce(struct kvm_vcpu *
default:
if (msr >= MSR_IA32_MC0_CTL &&
msr < MSR_IA32_MCx_CTL(bank_num)) {
- u32 offset = msr - MSR_IA32_MC0_CTL;
+ u32 offset = array_index_nospec(
+ msr - MSR_IA32_MC0_CTL,
+ MSR_IA32_MCx_CTL(bank_num) - MSR_IA32_MC0_CTL);
+
data = vcpu->arch.mce_banks[offset];
break;
}
