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KVM: nVMX: update last_nonleaf_level when initializing nested EPT

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commit fd19d3b45164466a4adce7cbff448ba9189e1427 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ladi Prosek 2017-10-05 11:10:22 +02:00 committed by Greg Kroah-Hartman
parent fb6da44f96
commit 28955b03fa
1 changed files with 1 additions and 0 deletions
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arch/x86/kvm/mmu.c
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@ -4169,6 +4169,7 @@ 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);
}