From: Sean Christopherson seanjc@google.com
commit c36b16d29f3af5f32fc1b2a3401bf48f71cabee1 upstream.
Use the kvm_for_each_vcpu() helper to iterate over vCPUs when encrypting VMSAs for SEV, which effectively switches to use online_vcpus instead of created_vcpus. This fixes a possible null-pointer dereference as created_vcpus does not guarantee a vCPU exists, since it is updated at the very beginning of KVM_CREATE_VCPU. created_vcpus exists to allow the bulk of vCPU creation to run in parallel, while still correctly restricting the max number of max vCPUs.
Fixes: ad73109ae7ec ("KVM: SVM: Provide support to launch and run an SEV-ES guest") Cc: stable@vger.kernel.org Cc: Brijesh Singh brijesh.singh@amd.com Cc: Tom Lendacky thomas.lendacky@amd.com Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20210331031936.2495277-2-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/svm/sev.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -564,6 +564,7 @@ static int sev_launch_update_vmsa(struct { struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; struct sev_data_launch_update_vmsa *vmsa; + struct kvm_vcpu *vcpu; int i, ret;
if (!sev_es_guest(kvm)) @@ -573,8 +574,8 @@ static int sev_launch_update_vmsa(struct if (!vmsa) return -ENOMEM;
- for (i = 0; i < kvm->created_vcpus; i++) { - struct vcpu_svm *svm = to_svm(kvm->vcpus[i]); + kvm_for_each_vcpu(i, vcpu, kvm) { + struct vcpu_svm *svm = to_svm(vcpu);
/* Perform some pre-encryption checks against the VMSA */ ret = sev_es_sync_vmsa(svm);