From f29a947a928e9464e177c97bb7b4bea0f4f0f765 Mon Sep 17 00:00:00 2001 From: Marios Pomonis Date: Wed, 11 Dec 2019 12:47:52 -0800 Subject: [PATCH] KVM: x86: Protect DR-based index computations from Spectre-v1/L1TF attacks commit ea740059ecb37807ba47b84b33d1447435a8d868 upstream. This fixes a Spectre-v1/L1TF vulnerability in __kvm_set_dr() and kvm_get_dr(). Both kvm_get_dr() and kvm_set_dr() (a wrapper of __kvm_set_dr()) are exported symbols so KVM should tream them conservatively from a security perspective. Fixes: 020df0794f57 ("KVM: move DR register access handling into generic code") Signed-off-by: Nick Finco Signed-off-by: Marios Pomonis Reviewed-by: Andrew Honig Reviewed-by: Jim Mattson Signed-off-by: Paolo Bonzini Signed-off-by: Ben Hutchings --- arch/x86/kvm/x86.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8bee2faf04dc1..730b3beeda6ae 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -801,9 +801,11 @@ static void kvm_update_dr7(struct kvm_vcpu *vcpu) static int __kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val) { + size_t size = ARRAY_SIZE(vcpu->arch.db); + switch (dr) { case 0 ... 3: - vcpu->arch.db[dr] = val; + vcpu->arch.db[array_index_nospec(dr, size)] = val; if (!(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)) vcpu->arch.eff_db[dr] = val; break; @@ -848,9 +850,11 @@ EXPORT_SYMBOL_GPL(kvm_set_dr); static int _kvm_get_dr(struct kvm_vcpu *vcpu, int dr, unsigned long *val) { + size_t size = ARRAY_SIZE(vcpu->arch.db); + switch (dr) { case 0 ... 3: - *val = vcpu->arch.db[dr]; + *val = vcpu->arch.db[array_index_nospec(dr, size)]; break; case 4: if (kvm_read_cr4_bits(vcpu, X86_CR4_DE)) -- 2.47.2