[RESEND] [PATCH 1/1] [CVE-2012-1601 [HARDY] KVM: Ensure all vcpus are consistent with in-kernel irqchip settings
Herton Ronaldo Krzesinski
herton.krzesinski at canonical.com
Thu Apr 26 12:45:08 UTC 2012
On Wed, Apr 25, 2012 at 05:14:17PM -0700, Brad Figg wrote:
> From: Avi Kivity <avi at redhat.com>
>
> CVE-2012-1601
>
> BugLink: http://bugs.launchpad.net/bugs/971685
>
> 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 at ellerman.id.au>
> Signed-off-by: Avi Kivity <avi at redhat.com>
> (backported from commit 3e515705a1f46beb1c942bb8043c16f8ac7b1e9e upstream)
> Signed-off-by: Brad Figg <brad.figg at canonical.com>
> ---
> arch/x86/kvm/x86.c | 9 +++++++++
> .../binary-custom.d/openvz/src/arch/x86/kvm/x86.c | 9 +++++++++
> .../openvz/src/include/linux/kvm_host.h | 2 ++
> .../binary-custom.d/openvz/src/virt/kvm/kvm_main.c | 5 +++++
> debian/binary-custom.d/xen/src/arch/x86/kvm/x86.c | 9 +++++++++
> .../xen/src/include/linux/kvm_host.h | 2 ++
> debian/binary-custom.d/xen/src/virt/kvm/kvm_main.c | 5 +++++
> include/linux/kvm_host.h | 2 ++
> virt/kvm/kvm_main.c | 5 +++++
> 9 files changed, 48 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 2085040..f036054 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1582,6 +1582,9 @@ long kvm_arch_vm_ioctl(struct file *filp,
> break;
> }
> case KVM_CREATE_IRQCHIP:
> + r = -EINVAL;
> + if (atomic_read(&kvm->online_vcpus))
> + goto out;
> r = -ENOMEM;
> kvm->arch.vpic = kvm_create_pic(kvm);
> if (kvm->arch.vpic) {
> @@ -3350,6 +3353,11 @@ 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;
> @@ -3435,6 +3443,7 @@ static void kvm_free_vcpus(struct kvm *kvm)
> }
> }
>
> + atomic_set(&kvm->online_vcpus, 0);
> }
>
> void kvm_arch_destroy_vm(struct kvm *kvm)
> diff --git a/debian/binary-custom.d/openvz/src/arch/x86/kvm/x86.c b/debian/binary-custom.d/openvz/src/arch/x86/kvm/x86.c
> index 2085040..f036054 100644
> --- a/debian/binary-custom.d/openvz/src/arch/x86/kvm/x86.c
> +++ b/debian/binary-custom.d/openvz/src/arch/x86/kvm/x86.c
> @@ -1582,6 +1582,9 @@ long kvm_arch_vm_ioctl(struct file *filp,
> break;
> }
> case KVM_CREATE_IRQCHIP:
> + r = -EINVAL;
> + if (atomic_read(&kvm->online_vcpus))
> + goto out;
> r = -ENOMEM;
> kvm->arch.vpic = kvm_create_pic(kvm);
> if (kvm->arch.vpic) {
> @@ -3350,6 +3353,11 @@ 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;
> @@ -3435,6 +3443,7 @@ static void kvm_free_vcpus(struct kvm *kvm)
> }
> }
>
> + atomic_set(&kvm->online_vcpus, 0);
> }
>
> void kvm_arch_destroy_vm(struct kvm *kvm)
> diff --git a/debian/binary-custom.d/openvz/src/include/linux/kvm_host.h b/debian/binary-custom.d/openvz/src/include/linux/kvm_host.h
> index 958e003..01055ae 100644
> --- a/debian/binary-custom.d/openvz/src/include/linux/kvm_host.h
> +++ b/debian/binary-custom.d/openvz/src/include/linux/kvm_host.h
> @@ -121,6 +121,7 @@ struct kvm {
> struct kvm_memory_slot memslots[KVM_MEMORY_SLOTS +
> KVM_PRIVATE_MEM_SLOTS];
> struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
> + atomic_t online_vcpus;
> struct list_head vm_list;
> struct file *filp;
> struct kvm_io_bus mmio_bus;
> @@ -306,5 +307,6 @@ struct kvm_stats_debugfs_item {
> struct dentry *dentry;
> };
> extern struct kvm_stats_debugfs_item debugfs_entries[];
> +bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu);
>
> #endif
> diff --git a/debian/binary-custom.d/openvz/src/virt/kvm/kvm_main.c b/debian/binary-custom.d/openvz/src/virt/kvm/kvm_main.c
> index 240156e..b128dcc 100644
> --- a/debian/binary-custom.d/openvz/src/virt/kvm/kvm_main.c
> +++ b/debian/binary-custom.d/openvz/src/virt/kvm/kvm_main.c
> @@ -798,12 +798,17 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
> goto vcpu_destroy;
>
> mutex_lock(&kvm->lock);
> + if (!kvm_vcpu_compatible(vcpu)) {
> + r = -EINVAL;
> + goto vcpu_destroy;
> + }
> if (kvm->vcpus[n]) {
> r = -EEXIST;
> mutex_unlock(&kvm->lock);
> goto vcpu_destroy;
> }
> kvm->vcpus[n] = vcpu;
> + atomic_inc(&kvm->online_vcpus);
> mutex_unlock(&kvm->lock);
>
> /* Now it's all set up, let userspace reach it */
> diff --git a/debian/binary-custom.d/xen/src/arch/x86/kvm/x86.c b/debian/binary-custom.d/xen/src/arch/x86/kvm/x86.c
> index 2085040..f036054 100644
> --- a/debian/binary-custom.d/xen/src/arch/x86/kvm/x86.c
> +++ b/debian/binary-custom.d/xen/src/arch/x86/kvm/x86.c
> @@ -1582,6 +1582,9 @@ long kvm_arch_vm_ioctl(struct file *filp,
> break;
> }
> case KVM_CREATE_IRQCHIP:
> + r = -EINVAL;
> + if (atomic_read(&kvm->online_vcpus))
> + goto out;
> r = -ENOMEM;
> kvm->arch.vpic = kvm_create_pic(kvm);
> if (kvm->arch.vpic) {
> @@ -3350,6 +3353,11 @@ 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;
> @@ -3435,6 +3443,7 @@ static void kvm_free_vcpus(struct kvm *kvm)
> }
> }
>
> + atomic_set(&kvm->online_vcpus, 0);
> }
>
> void kvm_arch_destroy_vm(struct kvm *kvm)
> diff --git a/debian/binary-custom.d/xen/src/include/linux/kvm_host.h b/debian/binary-custom.d/xen/src/include/linux/kvm_host.h
> index 958e003..01055ae 100644
> --- a/debian/binary-custom.d/xen/src/include/linux/kvm_host.h
> +++ b/debian/binary-custom.d/xen/src/include/linux/kvm_host.h
> @@ -121,6 +121,7 @@ struct kvm {
> struct kvm_memory_slot memslots[KVM_MEMORY_SLOTS +
> KVM_PRIVATE_MEM_SLOTS];
> struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
> + atomic_t online_vcpus;
> struct list_head vm_list;
> struct file *filp;
> struct kvm_io_bus mmio_bus;
> @@ -306,5 +307,6 @@ struct kvm_stats_debugfs_item {
> struct dentry *dentry;
> };
> extern struct kvm_stats_debugfs_item debugfs_entries[];
> +bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu);
>
> #endif
> diff --git a/debian/binary-custom.d/xen/src/virt/kvm/kvm_main.c b/debian/binary-custom.d/xen/src/virt/kvm/kvm_main.c
> index 240156e..b128dcc 100644
> --- a/debian/binary-custom.d/xen/src/virt/kvm/kvm_main.c
> +++ b/debian/binary-custom.d/xen/src/virt/kvm/kvm_main.c
> @@ -798,12 +798,17 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
> goto vcpu_destroy;
>
> mutex_lock(&kvm->lock);
> + if (!kvm_vcpu_compatible(vcpu)) {
> + r = -EINVAL;
> + goto vcpu_destroy;
> + }
> if (kvm->vcpus[n]) {
> r = -EEXIST;
> mutex_unlock(&kvm->lock);
> goto vcpu_destroy;
> }
> kvm->vcpus[n] = vcpu;
> + atomic_inc(&kvm->online_vcpus);
> mutex_unlock(&kvm->lock);
>
> /* Now it's all set up, let userspace reach it */
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 958e003..01055ae 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -121,6 +121,7 @@ struct kvm {
> struct kvm_memory_slot memslots[KVM_MEMORY_SLOTS +
> KVM_PRIVATE_MEM_SLOTS];
> struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
> + atomic_t online_vcpus;
> struct list_head vm_list;
> struct file *filp;
> struct kvm_io_bus mmio_bus;
> @@ -306,5 +307,6 @@ struct kvm_stats_debugfs_item {
> struct dentry *dentry;
> };
> extern struct kvm_stats_debugfs_item debugfs_entries[];
> +bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu);
>
> #endif
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 240156e..b128dcc 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -798,12 +798,17 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
> goto vcpu_destroy;
>
> mutex_lock(&kvm->lock);
> + if (!kvm_vcpu_compatible(vcpu)) {
> + r = -EINVAL;
You're still missing a mutex_unlock(&kvm->lock); here.
> + goto vcpu_destroy;
> + }
> if (kvm->vcpus[n]) {
> r = -EEXIST;
> mutex_unlock(&kvm->lock);
> goto vcpu_destroy;
> }
> kvm->vcpus[n] = vcpu;
> + atomic_inc(&kvm->online_vcpus);
> mutex_unlock(&kvm->lock);
>
> /* Now it's all set up, let userspace reach it */
> --
> 1.7.9.5
>
>
> --
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>
--
[]'s
Herton
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