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    Subject[PATCH 5.5 232/367] KVM: x86: Protect kvm_hv_msr_[get|set]_crash_data() from Spectre-v1/L1TF attacks
    Date
    From: Marios Pomonis <pomonis@google.com>

    commit 8618793750071d66028584a83ed0b4fa7eb4f607 upstream.

    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: 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
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

    --- a/arch/x86/kvm/hyperv.c
    +++ b/arch/x86/kvm/hyperv.c
    @@ -809,11 +809,12 @@ static int kvm_hv_msr_get_crash_data(str
    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(str
    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;
    }


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