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authorAndy Honig <ahonig@google.com>2013-11-20 10:23:22 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-12-20 07:45:07 -0800
commit0e03b79fc2eb224e09fde9f5f3495b5b15dac1ed (patch)
treebc19e4f82e0a885d70b1e6095c486a07543199c9 /arch/x86
parent9913f77411d04f56f600d900a6533c9518e6ee68 (diff)
downloadlinaro-lsk-0e03b79fc2eb224e09fde9f5f3495b5b15dac1ed.tar.gz
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')
-rw-r--r--arch/x86/kvm/lapic.c27
-rw-r--r--arch/x86/kvm/lapic.h4
-rw-r--r--arch/x86/kvm/x86.c40
3 files changed, 18 insertions, 53 deletions
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index b78a624edae..b468519f41f 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1706,7 +1706,6 @@ static void apic_sync_pv_eoi_from_guest(struct kvm_vcpu *vcpu,
void kvm_lapic_sync_from_vapic(struct kvm_vcpu *vcpu)
{
u32 data;
- void *vapic;
if (test_bit(KVM_APIC_PV_EOI_PENDING, &vcpu->arch.apic_attention))
apic_sync_pv_eoi_from_guest(vcpu, vcpu->arch.apic);
@@ -1714,9 +1713,8 @@ void kvm_lapic_sync_from_vapic(struct kvm_vcpu *vcpu)
if (!test_bit(KVM_APIC_CHECK_VAPIC, &vcpu->arch.apic_attention))
return;
- vapic = kmap_atomic(vcpu->arch.apic->vapic_page);
- data = *(u32 *)(vapic + offset_in_page(vcpu->arch.apic->vapic_addr));
- kunmap_atomic(vapic);
+ kvm_read_guest_cached(vcpu->kvm, &vcpu->arch.apic->vapic_cache, &data,
+ sizeof(u32));
apic_set_tpr(vcpu->arch.apic, data & 0xff);
}
@@ -1752,7 +1750,6 @@ void kvm_lapic_sync_to_vapic(struct kvm_vcpu *vcpu)
u32 data, tpr;
int max_irr, max_isr;
struct kvm_lapic *apic = vcpu->arch.apic;
- void *vapic;
apic_sync_pv_eoi_to_guest(vcpu, apic);
@@ -1768,18 +1765,24 @@ void kvm_lapic_sync_to_vapic(struct kvm_vcpu *vcpu)
max_isr = 0;
data = (tpr & 0xff) | ((max_isr & 0xf0) << 8) | (max_irr << 24);
- vapic = kmap_atomic(vcpu->arch.apic->vapic_page);
- *(u32 *)(vapic + offset_in_page(vcpu->arch.apic->vapic_addr)) = data;
- kunmap_atomic(vapic);
+ kvm_write_guest_cached(vcpu->kvm, &vcpu->arch.apic->vapic_cache, &data,
+ sizeof(u32));
}
-void kvm_lapic_set_vapic_addr(struct kvm_vcpu *vcpu, gpa_t vapic_addr)
+int kvm_lapic_set_vapic_addr(struct kvm_vcpu *vcpu, gpa_t vapic_addr)
{
- vcpu->arch.apic->vapic_addr = vapic_addr;
- if (vapic_addr)
+ if (vapic_addr) {
+ if (kvm_gfn_to_hva_cache_init(vcpu->kvm,
+ &vcpu->arch.apic->vapic_cache,
+ vapic_addr, sizeof(u32)))
+ return -EINVAL;
__set_bit(KVM_APIC_CHECK_VAPIC, &vcpu->arch.apic_attention);
- else
+ } else {
__clear_bit(KVM_APIC_CHECK_VAPIC, &vcpu->arch.apic_attention);
+ }
+
+ vcpu->arch.apic->vapic_addr = vapic_addr;
+ return 0;
}
int kvm_x2apic_msr_write(struct kvm_vcpu *vcpu, u32 msr, u64 data)
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index c730ac9fe80..c8b0d0d2da5 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -34,7 +34,7 @@ struct kvm_lapic {
*/
void *regs;
gpa_t vapic_addr;
- struct page *vapic_page;
+ struct gfn_to_hva_cache vapic_cache;
unsigned long pending_events;
unsigned int sipi_vector;
};
@@ -76,7 +76,7 @@ void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data);
void kvm_apic_write_nodecode(struct kvm_vcpu *vcpu, u32 offset);
void kvm_apic_set_eoi_accelerated(struct kvm_vcpu *vcpu, int vector);
-void kvm_lapic_set_vapic_addr(struct kvm_vcpu *vcpu, gpa_t vapic_addr);
+int kvm_lapic_set_vapic_addr(struct kvm_vcpu *vcpu, gpa_t vapic_addr);
void kvm_lapic_sync_from_vapic(struct kvm_vcpu *vcpu);
void kvm_lapic_sync_to_vapic(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e8ba99c3418..ad6a01605aa 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;
}