Fix PVC nil pointer dereference during migration-enabled volume expand

[wongma7]

What type of PR is this?

/kind bug

What this PR does / why we need it:

#111891 reported nil pointer dereference in KCM. Stack trace shows it happened because SetClaimResizer returned nil pvc and non-nil err, this nil PVC was passed to ClaimToClaimKey which panicked.

I think it is also possible for nil pointer dereference to happen at the informer Get which could also return nil pvc and non-nil err so I updated that as well to avoid dereferencing pvc object.

Finally, I updated every other place in this function that tries to call either util.ClaimToClaimKey(pvc) or util.GetPersistentVolumeClaimQualifiedName(pvc) for consistency and because they're unnecessary when we already have the key

Which issue(s) this PR fixes:

Fixes #111891

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[k8s-ci-robot]

Please note that we're already in Test Freeze for the release-1.25 branch. This means every merged PR will be automatically fast-forwarded via the periodic ci-fast-forward job to the release branch of the upcoming v1.25.0 release.

Fast forwards are scheduled to happen every 6 hours, whereas the most recent run was: Wed Aug 17 13:39:06 UTC 2022.

[k8s-ci-robot]

@wongma7: This issue is currently awaiting triage.

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[wongma7]

/sig storage

[mattcary]

/retest

(looks like flake failures)

[gnufied]

I checked the code btw and I think 1.24, 1.23 and master are safe. The bug might only exist in 1.22 or older versions of Kubernetes.

[wongma7]

yeah, because of 1ddd598 actually it looks like it is impossible for PatchPVCStatus and thus SetClaimResizer to return nil pvc in 1.23+*. How should I proceed, just open a PR directly to 1.22, or merge this in master as a 'code hygiene' kind of change and cherry-pick to 1.22?

[gnufied]

I kind of feel bad about leaving broken code in 1.22 because fix we are putting here does not directly fix the issue and there may be more "users" of the nil pvc and they may break too.

Lets accept this PR anyways and then while backporting to 1.22 fix the PatchPVCStatus function too?

[gnufied]

/lgtm

[gnufied]

/retest

[gnufied]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: gnufied, wongma7

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• pkg/controller/volume/expand/OWNERS [gnufied]
• pkg/volume/OWNERS [gnufied]

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[wongma7]

/test pull-kubernetes-e2e-gce-storage-snapshot