Looks similar to  bug 644640 , but this one is reproducible.

caryclark@, could you please help to triage?

The following revision refers to this bug:
  https://skia.googlesource.com/skia.git/+/bbfe92bc1dd2b0a65e63b3caed9873dbc4df522a

commit bbfe92bc1dd2b0a65e63b3caed9873dbc4df522a
Author: caryclark <caryclark@google.com>
Date: Mon Sep 19 13:00:35 2016

fix fuzzer bugs

Add a couple more cases where Op() fails and
returns false when the out of range input
values make the internal numeric unstable.

TBR=reed@google.com
BUG= 647834 ,  648068 
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2348263002

Review-Url: https://codereview.chromium.org/2348263002

[modify] https://crrev.com/bbfe92bc1dd2b0a65e63b3caed9873dbc4df522a/src/pathops/SkOpCoincidence.cpp
[modify] https://crrev.com/bbfe92bc1dd2b0a65e63b3caed9873dbc4df522a/tests/PathOpsOpTest.cpp

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c7397ecfff60fda69006f5cb837a99468fa4e6ca

commit c7397ecfff60fda69006f5cb837a99468fa4e6ca
Author: skia-deps-roller <skia-deps-roller@chromium.org>
Date: Mon Sep 19 13:58:02 2016

Roll src/third_party/skia/ e7a781274..bbfe92bc1 (1 commit).

https://chromium.googlesource.com/skia.git/+log/e7a7812744c2..bbfe92bc1dd2

$ git log e7a781274..bbfe92bc1 --date=short --no-merges --format='%ad %ae %s'
2016-09-19 caryclark fix fuzzer bugs

BUG= 647834 , 648068 

CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_precise_blink_rel
TBR=borenet@google.com

Review-Url: https://codereview.chromium.org/2343413002
Cr-Commit-Position: refs/heads/master@{#419448}

[modify] https://crrev.com/c7397ecfff60fda69006f5cb837a99468fa4e6ca/DEPS

ClusterFuzz has detected this issue as fixed in range 419434:419468.

Detailed report: https://cluster-fuzz.appspot.com/testcase?key=4604184664211456

Fuzzer: libfuzzer_skia_pathop_fuzzer
Job Type: libfuzzer_chrome_asan
Platform Id: linux

Crash Type: UNKNOWN READ
Crash Address: 0x000000000018
Crash State:
  next
  SkOpSpanBase::contains
  ordered
  
Fixed: https://cluster-fuzz.appspot.com/revisions?job=libfuzzer_chrome_asan&range=419434:419468

Minimized Testcase (0.49 Kb): https://cluster-fuzz.appspot.com/download/AMIfv951hfHk5DM4I8uh9AX6GR4PHtfShpQKRvSK6f5d6hUvZdKuuPXH8ky-g4gYvsNjQzMGuT9d2JGtU10Owv6cPUI7jzD8Y0856zDO2fffxAFovHqTgH-exjxNUmKlY3TyAX_wH307O6VyJcofeDXxREGsCc-SQg?testcase_id=4604184664211456

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.

Removing EditIssue view restrictions from ClusterFuzz filed bugs. If you believe that this issue should still be restricted, please reapply the label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot