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Subject[PATCH v2 02/13] KVM: x86: Protect kvm_hv_msr_[get|set]_crash_data() from Spectre-v1/L1TF attacks
From
This fixes Spectre-v1/L1TF vulnerabilities in kvm_hv_msr_get_crash_data()
and kvm_hv_msr_set_crash_data().
These functions contain index computations that use the
(attacker-controlled) MSR number.

Fixes: commit e7d9513b60e8 ("kvm/x86: added hyper-v crash msrs into kvm hyperv context")

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
---
arch/x86/kvm/hyperv.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 23ff65504d7e..26408434b9bc 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -809,11 +809,12 @@ static int kvm_hv_msr_get_crash_data(struct kvm_vcpu *vcpu,
u32 index, u64 *pdata)
{
struct kvm_hv *hv = &vcpu->kvm->arch.hyperv;
+ size_t size = ARRAY_SIZE(hv->hv_crash_param);

- if (WARN_ON_ONCE(index >= ARRAY_SIZE(hv->hv_crash_param)))
+ if (WARN_ON_ONCE(index >= size))
return -EINVAL;

- *pdata = hv->hv_crash_param[index];
+ *pdata = hv->hv_crash_param[array_index_nospec(index, size)];
return 0;
}

@@ -852,11 +853,12 @@ static int kvm_hv_msr_set_crash_data(struct kvm_vcpu *vcpu,
u32 index, u64 data)
{
struct kvm_hv *hv = &vcpu->kvm->arch.hyperv;
+ size_t size = ARRAY_SIZE(hv->hv_crash_param);

- if (WARN_ON_ONCE(index >= ARRAY_SIZE(hv->hv_crash_param)))
+ if (WARN_ON_ONCE(index >= size))
return -EINVAL;

- hv->hv_crash_param[index] = data;
+ hv->hv_crash_param[array_index_nospec(index, size)] = data;
return 0;
}

--
2.24.0.525.g8f36a354ae-goog
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