[1/2] KVM: nVMX: update last_nonleaf_level when initializing nested EPT

Message ID 1508936039-21254-2-git-send-email-stefan.bader@canonical.com
State New
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  • [1/2] KVM: nVMX: update last_nonleaf_level when initializing nested EPT
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Commit Message

Stefan Bader Oct. 25, 2017, 12:53 p.m.
From: Ladi Prosek <lprosek@redhat.com>

The function updates context->root_level but didn't call
update_last_nonleaf_level so the previous and potentially wrong value
was used for page walks.  For example, a zero value of last_nonleaf_level
would allow a potential out-of-bounds access in arch/x86/mmu/paging_tmpl.h's
walk_addr_generic function (CVE-2017-12188).

Fixes: 155a97a3d7c78b46cef6f1a973c831bc5a4f82bb
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

CVE-2017-12188

(cherry-picked from commit fd19d3b45164466a4adce7cbff448ba9189e1427)
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
---
 arch/x86/kvm/mmu.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Colin Ian King Oct. 25, 2017, 1:04 p.m. | #1
On 25/10/17 14:53, Stefan Bader wrote:
> From: Ladi Prosek <lprosek@redhat.com>
> 
> The function updates context->root_level but didn't call
> update_last_nonleaf_level so the previous and potentially wrong value
> was used for page walks.  For example, a zero value of last_nonleaf_level
> would allow a potential out-of-bounds access in arch/x86/mmu/paging_tmpl.h's
> walk_addr_generic function (CVE-2017-12188).
> 
> Fixes: 155a97a3d7c78b46cef6f1a973c831bc5a4f82bb
> Signed-off-by: Ladi Prosek <lprosek@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> 
> CVE-2017-12188
> 
> (cherry-picked from commit fd19d3b45164466a4adce7cbff448ba9189e1427)
> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
> ---
>  arch/x86/kvm/mmu.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index 7012de4..1e8a0e0 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -4158,6 +4158,7 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly)
>  
>  	update_permission_bitmask(vcpu, context, true);
>  	update_pkru_bitmask(vcpu, context, true);
> +	update_last_nonleaf_level(vcpu, context);
>  	reset_rsvds_bits_mask_ept(vcpu, context, execonly);
>  	reset_ept_shadow_zero_bits_mask(vcpu, context, execonly);
>  }
> 
Clean cherry pick. Looks good.

Acked-by: Colin Ian King <colin.king@canonical.com>

Patch

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 7012de4..1e8a0e0 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4158,6 +4158,7 @@  void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly)
 
 	update_permission_bitmask(vcpu, context, true);
 	update_pkru_bitmask(vcpu, context, true);
+	update_last_nonleaf_level(vcpu, context);
 	reset_rsvds_bits_mask_ept(vcpu, context, execonly);
 	reset_ept_shadow_zero_bits_mask(vcpu, context, execonly);
 }