APPLIED: [PATCH 1/1] [CVE-2012-1601] [LUCID] KVM: Ensure all vcpus are consistent with in-kernel irqchip settings

Submitted by Tim Gardner on April 26, 2012, 2:01 p.m.

Details

Message ID 4F995557.2000106@canonical.com
State New
Headers show

Commit Message

Tim Gardner April 26, 2012, 2:01 p.m.
On 04/25/2012 02:15 PM, Tim Gardner wrote:
> 

Given the extra cherry-pick, I'm resubmitting these patches. Pay
particular attention to kvm_arch_vm_ioctl() because my backport is
slightly different then Brad's.

rtg

Comments

Stefan Bader April 26, 2012, 2:30 p.m.
On 26.04.2012 16:01, Tim Gardner wrote:
> On 04/25/2012 02:15 PM, Tim Gardner wrote:
>>
> 
> Given the extra cherry-pick, I'm resubmitting these patches. Pay
> particular attention to kvm_arch_vm_ioctl() because my backport is
> slightly different then Brad's.
> 
> rtg

@@ -2285,6 +2285,9 @@ long kvm_arch_vm_ioctl(struct file *filp,
 			}
 		} else
 			goto out;
+		r = -EINVAL;
+		if (atomic_read(&kvm->online_vcpus))
+			goto out;
 		r = kvm_setup_default_irq_routing(kvm);
 		if (r) {
 			kfree(kvm->arch.vpic);

That might be slightly too late. The original patch adds the exit before calling
kvm_create_pic. Beside of probably other checks missing and not using the mutex
at all, the version above would have created the pic before bailing out.

Patch hide | download patch | download mbox

From 271465fe4695618b8a682934b9234ad387f21c36 Mon Sep 17 00:00:00 2001
From: Avi Kivity <avi@redhat.com>
Date: Mon, 5 Mar 2012 14:23:29 +0200
Subject: [PATCH 2/2] KVM: Ensure all vcpus are consistent with in-kernel
 irqchip settings

BugLink: http://bugs.launchpad.net/bugs/971685

CVE-2012-1601

If some vcpus are created before KVM_CREATE_IRQCHIP, then
irqchip_in_kernel() and vcpu->arch.apic will be inconsistent, leading
to potential NULL pointer dereferences.

Fix by:
- ensuring that no vcpus are installed when KVM_CREATE_IRQCHIP is called
- ensuring that a vcpu has an apic if it is installed after KVM_CREATE_IRQCHIP

This is somewhat long winded because vcpu->arch.apic is created without
kvm->lock held.

Based on earlier patch by Michael Ellerman.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Avi Kivity <avi@redhat.com>
(back ported from commit 3e515705a1f46beb1c942bb8043c16f8ac7b1e9e)

Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---
 arch/ia64/kvm/kvm-ia64.c |    5 +++++
 arch/x86/kvm/x86.c       |    8 ++++++++
 include/linux/kvm_host.h |    7 +++++++
 virt/kvm/kvm_main.c      |    4 ++++
 4 files changed, 24 insertions(+)

diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 2eb6365..416122b 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -1185,6 +1185,11 @@  out:
 
 #define PALE_RESET_ENTRY    0x80000000ffffffb0UL
 
+bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu)
+{
+	return irqchip_in_kernel(vcpu->kcm) == (vcpu->arch.apic != NULL);
+}
+
 int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 {
 	struct kvm_vcpu *v;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7000a5e..67030b8 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2285,6 +2285,9 @@  long kvm_arch_vm_ioctl(struct file *filp,
 			}
 		} else
 			goto out;
+		r = -EINVAL;
+		if (atomic_read(&kvm->online_vcpus))
+			goto out;
 		r = kvm_setup_default_irq_routing(kvm);
 		if (r) {
 			kfree(kvm->arch.vpic);
@@ -5007,6 +5010,11 @@  void kvm_arch_check_processor_compat(void *rtn)
 	kvm_x86_ops->check_processor_compatibility(rtn);
 }
 
+bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu)
+{
+	return irqchip_in_kernel(vcpu->kvm) == (vcpu->arch.apic != NULL);
+}
+
 int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 {
 	struct page *page;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 1296deb..624cf6b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -557,5 +557,12 @@  static inline bool kvm_vcpu_is_bsp(struct kvm_vcpu *vcpu)
 {
 	return vcpu->kvm->bsp_vcpu_id == vcpu->vcpu_id;
 }
+
+bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu);
+
+#else
+
+static inline bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu) { return true; }
+
 #endif
 #endif
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 42d7353..a27f14f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1872,6 +1872,10 @@  static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
 		goto vcpu_destroy;
 
 	mutex_lock(&kvm->lock);
+	if (!kvm_vcpu_compatible(vcpu)) {
+		r = -EINVAL;
+		goto unlock_vcpu_destroy;
+	}
 	if (atomic_read(&kvm->online_vcpus) == KVM_MAX_VCPUS) {
 		r = -EINVAL;
 		goto unlock_vcpu_destroy;
-- 
1.7.9.5