KVM: x86: Gracefully handle __vmalloc() failure during VM allocation

Check the result of __vmalloc() to avoid dereferencing a NULL pointer in
the event that allocation failres.

Fixes: d1e5b0e98e ("kvm: Make VM ioctl do valloc for some archs")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm.c

@@ -1949,6 +1949,10 @@ static struct kvm *svm_vm_alloc(void)
 	struct kvm_svm *kvm_svm = __vmalloc(sizeof(struct kvm_svm),
 					    GFP_KERNEL_ACCOUNT | __GFP_ZERO,
 					    PAGE_KERNEL);
+
+	if (!kvm_svm)
+		return NULL;
+
 	return &kvm_svm->kvm;
 }
 

arch/x86/kvm/vmx/vmx.c

@@ -6684,6 +6684,10 @@ static struct kvm *vmx_vm_alloc(void)
 	struct kvm_vmx *kvm_vmx = __vmalloc(sizeof(struct kvm_vmx),
 					    GFP_KERNEL_ACCOUNT | __GFP_ZERO,
 					    PAGE_KERNEL);
+
+	if (!kvm_vmx)
+		return NULL;
+
 	return &kvm_vmx->kvm;
 }