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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
	Roman Kagan <rkagan@virtuozzo.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Sasha Levin <sashal@kernel.org>,
	kvm@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 011/167] KVM: x86: hyperv: enforce vp_index < KVM_MAX_VCPUS
Date: Tue,  3 Sep 2019 12:22:43 -0400	[thread overview]
Message-ID: <20190903162519.7136-11-sashal@kernel.org> (raw)
In-Reply-To: <20190903162519.7136-1-sashal@kernel.org>

From: Vitaly Kuznetsov <vkuznets@redhat.com>

[ Upstream commit 9170200ec0ebad70e5b9902bc93e2b1b11456a3b ]

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 <vkuznets@redhat.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 229d996051653..73fa074b9089a 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;
-- 
2.20.1


       reply	other threads:[~2019-09-03 16:39 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190903162519.7136-1-sashal@kernel.org>
2019-09-03 16:22 ` Sasha Levin [this message]
2019-09-03 16:22 ` [PATCH AUTOSEL 4.19 012/167] KVM: x86: hyperv: consistently use 'hv_vcpu' for 'struct kvm_vcpu_hv' variables Sasha Levin
2019-09-03 16:22 ` [PATCH AUTOSEL 4.19 013/167] KVM: x86: hyperv: keep track of mismatched VP indexes Sasha Levin
2019-09-03 16:22 ` [PATCH AUTOSEL 4.19 014/167] KVM: hyperv: define VP assist page helpers Sasha Levin
2019-09-03 16:22 ` [PATCH AUTOSEL 4.19 015/167] x86/kvm/lapic: preserve gfn_to_hva_cache len on cache reinit Sasha Levin
2019-09-03 16:23 ` [PATCH AUTOSEL 4.19 065/167] KVM: VMX: Compare only a single byte for VMCS' "launched" in vCPU-run Sasha Levin
2019-09-03 16:23 ` [PATCH AUTOSEL 4.19 073/167] x86/kvmclock: set offset for kvm unstable clock Sasha Levin
2019-09-03 16:24 ` [PATCH AUTOSEL 4.19 092/167] kvm: mmu: Fix overflow on kvm mmu page limit calculation Sasha Levin
2019-09-03 16:24 ` [PATCH AUTOSEL 4.19 093/167] x86/kvm: move kvm_load/put_guest_xcr0 into atomic context Sasha Levin
2019-09-03 16:24 ` [PATCH AUTOSEL 4.19 094/167] KVM: x86: Always use 32-bit SMRAM save state for 32-bit kernels Sasha Levin
2019-09-03 16:24 ` [PATCH AUTOSEL 4.19 115/167] kvm: Check irqchip mode before assign irqfd Sasha Levin
2019-09-03 16:24 ` [PATCH AUTOSEL 4.19 132/167] KVM: x86: optimize check for valid PAT value Sasha Levin
2019-09-03 16:24 ` [PATCH AUTOSEL 4.19 133/167] KVM: VMX: Always signal #GP on WRMSR to MSR_IA32_CR_PAT with bad value Sasha Levin
2019-09-03 16:24 ` [PATCH AUTOSEL 4.19 134/167] KVM: VMX: Fix handling of #MC that occurs during VM-Entry Sasha Levin
2019-09-03 16:24 ` [PATCH AUTOSEL 4.19 135/167] KVM: VMX: check CPUID before allowing read/write of IA32_XSS Sasha Levin
2019-09-03 16:25 ` [PATCH AUTOSEL 4.19 162/167] virtio/s390: fix race on airq_areas[] Sasha Levin

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