Find it did not provide any possible suspects.
From CL, assigning to the concern owner --
https://chromium.googlesource.com/chromium/src/+log/784971913adcc32bdb22a92da6ac237a7de88a2b..ff280f67ab2bca6f1935e6d0061d9145a24a9526?pretty=fuller

Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/b9dc835015e914ded4f4f3db0bd9e95aaf7d7c03

@dsinclair -- Could you please look into the issue, kindly re-assign if this is not related to your changes.
Thank You.

https://pdfium-review.googlesource.com/c/2271/

Passing over to tsepez@ for once we get the safe numerics bit shift code.

https://pdfium.googlesource.com/pdfium/+/41c23536d10b04f56d0c4dfd1c36ee4664d9b7f9

ClusterFuzz has detected this issue as fixed in range 445740:445846.

Detailed report: https://cluster-fuzz.appspot.com/testcase?key=5684308758233088

Fuzzer: libfuzzer_pdf_psengine_fuzzer
Job Type: libfuzzer_chrome_ubsan
Platform Id: linux

Crash Type: Integer-overflow
Crash Address: 
Crash State:
  CPDF_PSEngine::DoOperator
  CPDF_PSProc::Execute
  CPDF_PSProc::Execute
  
Sanitizer: undefined (UBSAN)

Regressed: https://cluster-fuzz.appspot.com/revisions?job=libfuzzer_chrome_ubsan&range=413192:413325
Fixed: https://cluster-fuzz.appspot.com/revisions?job=libfuzzer_chrome_ubsan&range=445740:445846

Minimized Testcase (8.98 Kb): https://cluster-fuzz.appspot.com/download/AMIfv94XY9Y3GH4-uzLxrE5tJtAv4u7bWPb6ISR_vFwWx-3FaQe9Xjfyq0qeC5tkWBBEwDDT1VUgVwLo6afo1rMtBf_grpZVtyVrpepxGq3X8rpwKw-YyvEy0EHo06dGmoBrBlzz1ZpXE8hLwY5B100noG0tHiQrJ5fLtiBtytCBj8eRHay9rC518JJdFt28xqcazyCrIpBpVtmFxl1WPsoG7DaDc9doJW1YwZ-BcZz4EW-6vt5AWzbT_PLCJwjY6cfu4WgM9Xow8hOUAFzQsHrAuwBfSQxcODR-1TiklGXKP6dpgdEQpgsTHc4NGT1WMajDCvgFqHRsHz9Slazc_iDRE0-Pu6TkrV8_LOG0PaLURKR5d8yN_FI?testcase_id=5684308758233088

See https://chromium.googlesource.com/chromium/src/+/master/testing/libfuzzer/reproducing.md for more information.

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.