KVM: x86/mmu: Initialize kvm_page_fault's pfn and hva to error values

Explicitly set "pfn" and "hva" to error values in kvm_mmu_do_page_fault()
to harden KVM against using "uninitialized" values.  In quotes because the
fields are actually zero-initialized, and zero is a legal value for both
page frame numbers and virtual addresses.  E.g. failure to set "pfn" prior
to creating an SPTE could result in KVM pointing at physical address '0',
which is far less desirable than KVM generating a SPTE with reserved PA
bits set and thus effectively killing the VM.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Message-ID: <20240228024147.41573-16-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index dfd9ff3836634e05e17c6dad37d75e2e85e5a491..ce2fcd19ba6be0ba0025f32bf57791254158efce 100644 (file)
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -307,6 +307,9 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
                .req_level = PG_LEVEL_4K,
                .goal_level = PG_LEVEL_4K,
                .is_private = err & PFERR_PRIVATE_ACCESS,
+
+               .pfn = KVM_PFN_ERR_FAULT,
+               .hva = KVM_HVA_ERR_BAD,
        };
        int r;