Predator and CL did not provide any possible suspects.
Using Code Search for the file, "PaintLayerScrollableArea.cpp" assigning to the concern owner.
Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/06d238a9e9311f536cb7c930ee6b6c28987c60ed

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

This looks pretty straightforward, crashing on accessing the PaintLayerScrollableArea before the first layout has finished.  I think it's incorrect to assume that 'HasOverflowClip()' and '!!GetScrollableArea()' are always equivalent.

This has nothing to do with my change; reassigning to skobes@, for scroll anchoring implications.

ClusterFuzz has detected this issue as fixed in range 481254:481414.

Detailed report: https://clusterfuzz.com/testcase?key=4537231380578304

Fuzzer: inferno_webbot
Job Type: windows_asan_chrome
Platform Id: windows

Crash Type: Null-dereference READ
Crash Address: 0x000000a4
Crash State:
  blink::PaintLayerScrollableArea::ShouldPerformScrollAnchoring
  blink::LayoutBlock::UpdateLayout
  blink::LayoutBlockFlow::PositionAndLayoutOnceIfNeeded
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=windows_asan_chrome&range=480776:480854
Fixed: https://clusterfuzz.com/revisions?job=windows_asan_chrome&range=481254:481414

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=4537231380578304


See https://dev.chromium.org/Home/chromium-security/bugs/reproducing-clusterfuzz-bugs for more information.

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

ClusterFuzz testcase 4537231380578304 is verified as fixed, so closing issue.

If this is incorrect, please add ClusterFuzz-Wrong label and re-open the issue.