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

Herton Ronaldo Krzesinski herton.krzesinski at canonical.com
Thu Apr 26 13:38:33 UTC 2012


On Thu, Apr 26, 2012 at 07:24:26AM -0600, Tim Gardner wrote:
> On 04/26/2012 06:57 AM, Stefan Bader wrote:
> > On 26.04.2012 14:52, Tim Gardner wrote:
> >> So this patch causes a compile error. I've attached the correction. I
> >> suggest that it just be squashed into the original commit.
> >>
> >> rtg
> >>
> >>
> >>
> >>
> > Maybe we want to pick up the patch that introduced it:
> > 
> > 
> > commit d780592b99d7d8a5ff905f6bacca519d4a342c76
> > Author: Jan Kiszka <jan.kiszka at siemens.com>
> > Date:   Mon May 23 10:33:05 2011 +0200
> > 
> >     KVM: Clean up error handling during VCPU creation
> > 
> > Not sure all the jumps to vcpu_destroy before would otherwise do the right thing...
> > 
> > 
> > 
> > 
> 
> OK, here is the real solution. d780592b99d7d8a5ff905f6bacca519d4a342c76
> and 3e515705a1f46beb1c942bb8043c16f8ac7b1e9e are clean cherry-picks. No
> backport required.
> 
> rtg
> -- 
> Tim Gardner tim.gardner at canonical.com

> From cf94f3808929793e07361d2b7bc6edb44969d47f Mon Sep 17 00:00:00 2001
> From: Jan Kiszka <jan.kiszka at siemens.com>
> Date: Mon, 23 May 2011 10:33:05 +0200
> Subject: [PATCH 1/2] KVM: Clean up error handling during VCPU creation
> 
> BugLink: http://bugs.launchpad.net/bugs/971685
> 
> CVE-2012-1601
> 
> So far kvm_arch_vcpu_setup is responsible for freeing the vcpu struct if
> it fails. Move this confusing resonsibility back into the hands of
> kvm_vm_ioctl_create_vcpu. Only kvm_arch_vcpu_setup of x86 is affected,
> all other archs cannot fail.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka at siemens.com>
> Signed-off-by: Avi Kivity <avi at redhat.com>
> (cherry picked from commit d780592b99d7d8a5ff905f6bacca519d4a342c76)
> 
> Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
> ---
>  arch/x86/kvm/x86.c  |    5 -----
>  virt/kvm/kvm_main.c |   11 ++++++-----
>  2 files changed, 6 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 8e15578..d829351 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6145,12 +6145,7 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
>  	if (r == 0)
>  		r = kvm_mmu_setup(vcpu);
>  	vcpu_put(vcpu);
> -	if (r < 0)
> -		goto free_vcpu;
>  
> -	return 0;
> -free_vcpu:
> -	kvm_x86_ops->vcpu_free(vcpu);
>  	return r;
>  }
>  
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 96ebc06..7d6b8e3 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1615,18 +1615,18 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
>  
>  	r = kvm_arch_vcpu_setup(vcpu);
>  	if (r)
> -		return r;
> +		goto vcpu_destroy;
>  
>  	mutex_lock(&kvm->lock);
>  	if (atomic_read(&kvm->online_vcpus) == KVM_MAX_VCPUS) {
>  		r = -EINVAL;
> -		goto vcpu_destroy;
> +		goto unlock_vcpu_destroy;
>  	}
>  
>  	kvm_for_each_vcpu(r, v, kvm)
>  		if (v->vcpu_id == id) {
>  			r = -EEXIST;
> -			goto vcpu_destroy;
> +			goto unlock_vcpu_destroy;
>  		}
>  
>  	BUG_ON(kvm->vcpus[atomic_read(&kvm->online_vcpus)]);
> @@ -1636,7 +1636,7 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
>  	r = create_vcpu_fd(vcpu);
>  	if (r < 0) {
>  		kvm_put_kvm(kvm);
> -		goto vcpu_destroy;
> +		goto unlock_vcpu_destroy;
>  	}
>  
>  	kvm->vcpus[atomic_read(&kvm->online_vcpus)] = vcpu;
> @@ -1650,8 +1650,9 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
>  	mutex_unlock(&kvm->lock);
>  	return r;
>  
> -vcpu_destroy:
> +unlock_vcpu_destroy:
>  	mutex_unlock(&kvm->lock);
> +vcpu_destroy:
>  	kvm_arch_vcpu_destroy(vcpu);
>  	return r;
>  }
> -- 
> 1.7.9.5
> 

> From 08a5694c9cce61f44bc4909ecb947586105374a3 Mon Sep 17 00:00:00 2001
> From: Avi Kivity <avi at 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 at ellerman.id.au>
> Signed-off-by: Avi Kivity <avi at redhat.com>
> (cherry picked from commit 3e515705a1f46beb1c942bb8043c16f8ac7b1e9e)
> 
> Signed-off-by: Tim Gardner <tim.gardner at 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 8213efe..a874213 100644
> --- a/arch/ia64/kvm/kvm-ia64.c
> +++ b/arch/ia64/kvm/kvm-ia64.c
> @@ -1168,6 +1168,11 @@ 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 d829351..bf59dfc 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3439,6 +3439,9 @@ long kvm_arch_vm_ioctl(struct file *filp,
>  		r = -EEXIST;
>  		if (kvm->arch.vpic)
>  			goto create_irqchip_unlock;
> +		r = -EINVAL;
> +		if (atomic_read(&kvm->online_vcpus))
> +			goto create_irqchip_unlock;
>  		r = -ENOMEM;
>  		vpic = kvm_create_pic(kvm);
>  		if (vpic) {
> @@ -6218,6 +6221,11 @@ 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 31ebb59..d70a250 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -730,6 +730,13 @@ 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
>  
>  #ifdef __KVM_HAVE_DEVICE_ASSIGNMENT
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 7d6b8e3..f9013d1 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1618,6 +1618,10 @@ 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
> 

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-- 
[]'s
Herton



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