KVM: nVMX: Fix size checks in vmx_set_nested_state [Linux 5.1]

KVM: nVMX: Fix size checks in vmx_set_nested_state [Linux 5.1]

This Linux kernel change "KVM: nVMX: Fix size checks in vmx_set_nested_state" is included in the Linux 5.1 release. This change is authored by Jim Mattson <jmattson [at] google.com> on Thu Jan 17 11:55:58 2019 -0800. The commit for this change in Linux stable tree is e8ab8d2 (patch).

KVM: nVMX: Fix size checks in vmx_set_nested_state

The size checks in vmx_nested_state are wrong because the calculations
are made based on the size of a pointer to a struct kvm_nested_state
rather than the size of a struct kvm_nested_state.

Reported-by: Felix Wilhelm  <fwilhelm@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Drew Schmitt <dasch@google.com>
Reviewed-by: Marc Orr <marcorr@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Fixes: 8fcc4b5923af5de58b80b53a069453b135693304
Cc: stable@ver.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

There are 4 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 arch/x86/kvm/vmx/nested.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 6401eb7..0c601d0 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -5423,7 +5423,7 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
        return ret;

    /* Empty 'VMXON' state is permitted */
-   if (kvm_state->size < sizeof(kvm_state) + sizeof(*vmcs12))
+   if (kvm_state->size < sizeof(*kvm_state) + sizeof(*vmcs12))
        return 0;

    if (kvm_state->vmx.vmcs_pa != -1ull) {
@@ -5467,7 +5467,7 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
        vmcs12->vmcs_link_pointer != -1ull) {
        struct vmcs12 *shadow_vmcs12 = get_shadow_vmcs12(vcpu);

-       if (kvm_state->size < sizeof(kvm_state) + 2 * sizeof(*vmcs12))
+       if (kvm_state->size < sizeof(*kvm_state) + 2 * sizeof(*vmcs12))
            return -EINVAL;

        if (copy_from_user(shadow_vmcs12,

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