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kvm: x86/vmx: Use kzalloc for cached_vmcs12
commit3a33d030da
upstream. This changes the allocation of cached_vmcs12 to use kzalloc instead of kmalloc. This removes the information leak found by Syzkaller (see Reported-by) in this case and prevents similar leaks from happening based on cached_vmcs12. It also changes vmx_get_nested_state to copy out the full 4k VMCS12_SIZE in copy_to_user rather than only the size of the struct. Tested: rebuilt against head, booted, and ran the syszkaller repro https://syzkaller.appspot.com/text?tag=ReproC&x=174efca3400000 without observing any problems. Reported-by: syzbot+ded1696f6b50b615b630@syzkaller.appspotmail.com Fixes:8fcc4b5923
Cc: stable@vger.kernel.org Signed-off-by: Tom Roeder <tmroeder@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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1 changed files with 8 additions and 4 deletions
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@ -8290,11 +8290,11 @@ static int enter_vmx_operation(struct kvm_vcpu *vcpu)
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if (r < 0)
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goto out_vmcs02;
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vmx->nested.cached_vmcs12 = kmalloc(VMCS12_SIZE, GFP_KERNEL);
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vmx->nested.cached_vmcs12 = kzalloc(VMCS12_SIZE, GFP_KERNEL);
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if (!vmx->nested.cached_vmcs12)
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goto out_cached_vmcs12;
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vmx->nested.cached_shadow_vmcs12 = kmalloc(VMCS12_SIZE, GFP_KERNEL);
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vmx->nested.cached_shadow_vmcs12 = kzalloc(VMCS12_SIZE, GFP_KERNEL);
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if (!vmx->nested.cached_shadow_vmcs12)
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goto out_cached_shadow_vmcs12;
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@ -13984,13 +13984,17 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
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else if (enable_shadow_vmcs && !vmx->nested.sync_shadow_vmcs)
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copy_shadow_to_vmcs12(vmx);
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if (copy_to_user(user_kvm_nested_state->data, vmcs12, sizeof(*vmcs12)))
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/*
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* Copy over the full allocated size of vmcs12 rather than just the size
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* of the struct.
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*/
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if (copy_to_user(user_kvm_nested_state->data, vmcs12, VMCS12_SIZE))
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return -EFAULT;
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if (nested_cpu_has_shadow_vmcs(vmcs12) &&
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vmcs12->vmcs_link_pointer != -1ull) {
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if (copy_to_user(user_kvm_nested_state->data + VMCS12_SIZE,
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get_shadow_vmcs12(vcpu), sizeof(*vmcs12)))
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get_shadow_vmcs12(vcpu), VMCS12_SIZE))
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return -EFAULT;
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}
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