From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vitaly Kuznetsov Subject: [PATCH v6 1/7] KVM: x86: hyperv: enforce vp_index < KVM_MAX_VCPUS Date: Wed, 26 Sep 2018 19:02:53 +0200 Message-ID: <20180926170259.29796-2-vkuznets@redhat.com> References: <20180926170259.29796-1-vkuznets@redhat.com> Cc: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Roman Kagan , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , "Michael Kelley (EOSG)" , Mohammed Gamal , Cathy Avery , Wanpeng Li , linux-kernel@vger.kernel.org To: kvm@vger.kernel.org Return-path: In-Reply-To: <20180926170259.29796-1-vkuznets@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Hyper-V TLFS (5.0b) states: > Virtual processors are identified by using an index (VP index). The > maximum number of virtual processors per partition supported by the > current implementation of the hypervisor can be obtained through CPUID > leaf 0x40000005. A virtual processor index must be less than the > maximum number of virtual processors per partition. Forbid userspace to set VP_INDEX above KVM_MAX_VCPUS. get_vcpu_by_vpidx() can now be optimized to bail early when supplied vpidx is >= KVM_MAX_VCPUS. Signed-off-by: Vitaly Kuznetsov Reviewed-by: Roman Kagan --- arch/x86/kvm/hyperv.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 01d209ab5481..0cd597b0f754 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -132,8 +132,10 @@ static struct kvm_vcpu *get_vcpu_by_vpidx(struct kvm *kvm, u32 vpidx) struct kvm_vcpu *vcpu = NULL; int i; - if (vpidx < KVM_MAX_VCPUS) - vcpu = kvm_get_vcpu(kvm, vpidx); + if (vpidx >= KVM_MAX_VCPUS) + return NULL; + + vcpu = kvm_get_vcpu(kvm, vpidx); if (vcpu && vcpu_to_hv_vcpu(vcpu)->vp_index == vpidx) return vcpu; kvm_for_each_vcpu(i, vcpu, kvm) @@ -1044,7 +1046,7 @@ static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host) switch (msr) { case HV_X64_MSR_VP_INDEX: - if (!host) + if (!host || (u32)data >= KVM_MAX_VCPUS) return 1; hv->vp_index = (u32)data; break; -- 2.17.1