Messages in this thread Patch in this message | | | From | Like Xu <> | Subject | [PATCH] KVM: x86/cpuid: Exclude unpermitted xfeatures for vcpu->arch.guest_supported_xcr0 | Date | Sun, 23 Jan 2022 13:50:25 +0800 |
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From: Like Xu <likexu@tencent.com>
A malicious user space can bypass xstate_get_guest_group_perm() in the KVM_GET_SUPPORTED_CPUID mechanism and obtain unpermitted xfeatures, since the validity check of xcr0 depends only on guest_supported_xcr0.
Fixes: 445ecdf79be0 ("kvm: x86: Exclude unpermitted xfeatures at KVM_GET_SUPPORTED_CPUID") Signed-off-by: Like Xu <likexu@tencent.com> --- arch/x86/kvm/cpuid.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 3902c28fb6cb..1bd4d560cbdd 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -266,7 +266,8 @@ static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) vcpu->arch.guest_supported_xcr0 = 0; else vcpu->arch.guest_supported_xcr0 = - (best->eax | ((u64)best->edx << 32)) & supported_xcr0; + (best->eax | ((u64)best->edx << 32)) & + (supported_xcr0 & xstate_get_guest_group_perm()); /* * Bits 127:0 of the allowed SECS.ATTRIBUTES (CPUID.0x12.0x1) enumerate -- 2.33.1
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