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

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

This may have been caused by some recent upstream patches, filed http://bugzilla.maptools.org/show_bug.cgi?id=2721

Could you provide the test case in http://bugzilla.maptools.org/show_bug.cgi?id=2721 so we can diagnose what happens ? Thanks

The following revision refers to this bug:
  https://pdfium.googlesource.com/pdfium/+/d3c6f8119a4c6cd143c6f2f3f874705f57afaf36

commit d3c6f8119a4c6cd143c6f2f3f874705f57afaf36
Author: Nicolas Pena <npm@chromium.org>
Date: Fri Jul 28 18:39:37 2017

LibTIFF: upstream patch to fix null dereference

This CL applies this patch that fixes a recent null dereference regression:
https://github.com/vadz/libtiff/commit/57f4b28c00d78bd5d74768585d0e46b2e12e94f7

Bug:  chromium:743621 
Change-Id: I0f9d4321dc6ea71dd31cf0ba8420cc25d401f0d8
Reviewed-on: https://pdfium-review.googlesource.com/9490
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Nicolás Peña <npm@chromium.org>

[modify] https://crrev.com/d3c6f8119a4c6cd143c6f2f3f874705f57afaf36/third_party/libtiff/tif_getimage.c
[add] https://crrev.com/d3c6f8119a4c6cd143c6f2f3f874705f57afaf36/third_party/libtiff/0026-upstream-null-dereference.patch
[modify] https://crrev.com/d3c6f8119a4c6cd143c6f2f3f874705f57afaf36/third_party/libtiff/README.pdfium

ClusterFuzz has detected this issue as fixed in range 490594:490630.

Detailed report: https://clusterfuzz.com/testcase?key=5030391504437248

Fuzzer: libFuzzer_pdf_codec_tiff_fuzzer
Job Type: libfuzzer_chrome_asan
Platform Id: linux

Crash Type: Null-dereference WRITE
Crash Address: 0x000000000000
Crash State:
  horizontalAccumulate16
  PixarLogDecode
  TIFFReadEncodedTile
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan&range=486555:486672
Fixed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan&range=490594:490630

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=5030391504437248


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 5030391504437248 is verified as fixed, so closing issue as verified.

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