diff options
| author | Andy Honig <ahonig@google.com> | 2013-11-20 10:23:22 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-12-20 07:45:07 -0800 |
| commit | 0e03b79fc2eb224e09fde9f5f3495b5b15dac1ed (patch) | |
| tree | bc19e4f82e0a885d70b1e6095c486a07543199c9 /arch/x86/kvm/x86.c | |
| parent | 9913f77411d04f56f600d900a6533c9518e6ee68 (diff) | |
KVM: x86: Convert vapic synchronization to _cached functions (CVE-2013-6368)
commit fda4e2e85589191b123d31cdc21fd33ee70f50fd upstream.
In kvm_lapic_sync_from_vapic and kvm_lapic_sync_to_vapic there is the
potential to corrupt kernel memory if userspace provides an address that
is at the end of a page. This patches concerts those functions to use
kvm_write_guest_cached and kvm_read_guest_cached. It also checks the
vapic_address specified by userspace during ioctl processing and returns
an error to userspace if the address is not a valid GPA.
This is generally not guest triggerable, because the required write is
done by firmware that runs before the guest. Also, it only affects AMD
processors and oldish Intel that do not have the FlexPriority feature
(unless you disable FlexPriority, of course; then newer processors are
also affected).
Fixes: b93463aa59d6 ('KVM: Accelerated apic support')
Reported-by: Andrew Honig <ahonig@google.com>
Signed-off-by: Andrew Honig <ahonig@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86/kvm/x86.c')
| -rw-r--r-- | arch/x86/kvm/x86.c | 40 |
1 files changed, 1 insertions, 39 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e8ba99c34180..ad6a01605aaa 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3138,8 +3138,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp, r = -EFAULT; if (copy_from_user(&va, argp, sizeof va)) goto out; - r = 0; - kvm_lapic_set_vapic_addr(vcpu, va.vapic_addr); + r = kvm_lapic_set_vapic_addr(vcpu, va.vapic_addr); break; } case KVM_X86_SETUP_MCE: { @@ -5539,36 +5538,6 @@ static void post_kvm_run_save(struct kvm_vcpu *vcpu) !kvm_event_needs_reinjection(vcpu); } -static int vapic_enter(struct kvm_vcpu *vcpu) -{ - struct kvm_lapic *apic = vcpu->arch.apic; - struct page *page; - - if (!apic || !apic->vapic_addr) - return 0; - - page = gfn_to_page(vcpu->kvm, apic->vapic_addr >> PAGE_SHIFT); - if (is_error_page(page)) - return -EFAULT; - - vcpu->arch.apic->vapic_page = page; - return 0; -} - -static void vapic_exit(struct kvm_vcpu *vcpu) -{ - struct kvm_lapic *apic = vcpu->arch.apic; - int idx; - - if (!apic || !apic->vapic_addr) - return; - - idx = srcu_read_lock(&vcpu->kvm->srcu); - kvm_release_page_dirty(apic->vapic_page); - mark_page_dirty(vcpu->kvm, apic->vapic_addr >> PAGE_SHIFT); - srcu_read_unlock(&vcpu->kvm->srcu, idx); -} - static void update_cr8_intercept(struct kvm_vcpu *vcpu) { int max_irr, tpr; @@ -5889,11 +5858,6 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) struct kvm *kvm = vcpu->kvm; vcpu->srcu_idx = srcu_read_lock(&kvm->srcu); - r = vapic_enter(vcpu); - if (r) { - srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); - return r; - } r = 1; while (r > 0) { @@ -5951,8 +5915,6 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); - vapic_exit(vcpu); - return r; } |