Fixes nil pointer panic on autoscaling types conversion

[yue9944882]

/kind bug
/sig autoscaling
/priority critical-urgent

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #70806

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Fixes apiserver nil pointer panics when requesting v2beta1 autoscaling object metrics

[yue9944882]

this is another surprise when i walk thru all the autoscaling conversion. should do a deep copy here.

[liggitt]

conversion is not required to make copies of the input object values

[yue9944882]

conversion is not required to make copies of the input object values

@liggitt if we call this conversion directly (not recommended tho), modifying the input obj will propagates to the output. is that okay? 🤔

[yue9944882]

edit: mmm.. quantity might be special.. we don't actually modify that in-place

[liggitt]

if we call this conversion directly (not recommended tho), modifying the input obj will propagates to the output. is that okay?

Yes. Generated conversions share memory between the input and output object where possible:

kubernetes/pkg/apis/core/v1/zz_generated.conversion.go

Lines 7457 to 7494 in a0c2788

	func autoConvert_v1_VolumeSource_To_core_VolumeSource(in *v1.VolumeSource, out *core.VolumeSource, s conversion.Scope) error {
	out.HostPath = (*core.HostPathVolumeSource)(unsafe.Pointer(in.HostPath))
	out.EmptyDir = (*core.EmptyDirVolumeSource)(unsafe.Pointer(in.EmptyDir))
	out.GCEPersistentDisk = (*core.GCEPersistentDiskVolumeSource)(unsafe.Pointer(in.GCEPersistentDisk))
	out.AWSElasticBlockStore = (*core.AWSElasticBlockStoreVolumeSource)(unsafe.Pointer(in.AWSElasticBlockStore))
	out.GitRepo = (*core.GitRepoVolumeSource)(unsafe.Pointer(in.GitRepo))
	out.Secret = (*core.SecretVolumeSource)(unsafe.Pointer(in.Secret))
	out.NFS = (*core.NFSVolumeSource)(unsafe.Pointer(in.NFS))
	out.ISCSI = (*core.ISCSIVolumeSource)(unsafe.Pointer(in.ISCSI))
	out.Glusterfs = (*core.GlusterfsVolumeSource)(unsafe.Pointer(in.Glusterfs))
	out.PersistentVolumeClaim = (*core.PersistentVolumeClaimVolumeSource)(unsafe.Pointer(in.PersistentVolumeClaim))
	out.RBD = (*core.RBDVolumeSource)(unsafe.Pointer(in.RBD))
	out.FlexVolume = (*core.FlexVolumeSource)(unsafe.Pointer(in.FlexVolume))
	out.Cinder = (*core.CinderVolumeSource)(unsafe.Pointer(in.Cinder))
	out.CephFS = (*core.CephFSVolumeSource)(unsafe.Pointer(in.CephFS))
	out.Flocker = (*core.FlockerVolumeSource)(unsafe.Pointer(in.Flocker))
	out.DownwardAPI = (*core.DownwardAPIVolumeSource)(unsafe.Pointer(in.DownwardAPI))
	out.FC = (*core.FCVolumeSource)(unsafe.Pointer(in.FC))
	out.AzureFile = (*core.AzureFileVolumeSource)(unsafe.Pointer(in.AzureFile))
	out.ConfigMap = (*core.ConfigMapVolumeSource)(unsafe.Pointer(in.ConfigMap))
	out.VsphereVolume = (*core.VsphereVirtualDiskVolumeSource)(unsafe.Pointer(in.VsphereVolume))
	out.Quobyte = (*core.QuobyteVolumeSource)(unsafe.Pointer(in.Quobyte))
	out.AzureDisk = (*core.AzureDiskVolumeSource)(unsafe.Pointer(in.AzureDisk))
	out.PhotonPersistentDisk = (*core.PhotonPersistentDiskVolumeSource)(unsafe.Pointer(in.PhotonPersistentDisk))
	if in.Projected != nil {
	in, out := &in.Projected, &out.Projected
	*out = new(core.ProjectedVolumeSource)
	if err := Convert_v1_ProjectedVolumeSource_To_core_ProjectedVolumeSource(*in, *out, s); err != nil {
	return err
	}
	} else {
	out.Projected = nil
	}
	out.PortworxVolume = (*core.PortworxVolumeSource)(unsafe.Pointer(in.PortworxVolume))
	out.ScaleIO = (*core.ScaleIOVolumeSource)(unsafe.Pointer(in.ScaleIO))
	out.StorageOS = (*core.StorageOSVolumeSource)(unsafe.Pointer(in.StorageOS))
	return nil
	}

[yue9944882]

/assign @liggitt
/cc @kubernetes/sig-autoscaling-bugs

[liggitt]

needs a test demonstrating the bug and that this fixes the issue

[liggitt]

does this have the same issue:

kubernetes/pkg/apis/autoscaling/v2beta1/conversion.go

Lines 188 to 189 in a0c2788

	targetAverageValue := *in.Target.AverageValue
	out.TargetAverageValue = targetAverageValue

[yue9944882]

@liggitt is it ready for cherry-picks?

[liggitt]

/lgtm
/approve

let's wait for green CI before opening picks

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: liggitt, yue9944882

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[liggitt]

@yue9944882 can you open the picks for this to release-1.13 and release-1.12?

[yue9944882]

@liggitt sure, done (wake up hour here)