Predator and CL did not provide any possible suspects.
Using Code Search for the file, "GrTessellator.cpp" assigning to the concern owner who might be related.

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

ClusterFuzz has detected this issue as fixed in range 493187:493236.

Detailed report: https://clusterfuzz.com/testcase?key=6251398277890048

Fuzzer: libFuzzer_paint_op_buffer_fuzzer
Job Type: libfuzzer_chrome_asan_debug
Platform Id: linux

Crash Type: Stack-overflow
Crash Address: 0x7ffdea2e5ba8
Crash State:
  set_top
  merge_edges_below
  merge_collinear_edges
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan_debug&range=491830:491916
Fixed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan_debug&range=493187:493236

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6251398277890048

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.

ClusterFuzz testcase 6251398277890048 is verified as fixed, so closing issue as verified.

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