See: https://skia.googlesource.com/skia/+/3ed4781ee1bd5af9b3ee2623e5356e86ce36e812/src/shaders/gradients/SkSweepGradient.cpp#21

Looks like some missing validation on this kind of shader.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3b05219769a0ae47c640126623619bc07abe826f

commit 3b05219769a0ae47c640126623619bc07abe826f
Author: Vladimir Levin <vmpstr@chromium.org>
Date: Fri Sep 08 01:51:00 2017

cc: Validate angles in sweep gradients.

This patch ensures that we validate start/end angles in shader
validation for sweep gradients.

R=enne@chromium.org

Bug:  763121 
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ia66bc51d8f9c24c40f22c1e962e70123b2ad7262
Reviewed-on: https://chromium-review.googlesource.com/656499
Reviewed-by: enne <enne@chromium.org>
Commit-Queue: Vladimir Levin <vmpstr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#500481}
[modify] https://crrev.com/3b05219769a0ae47c640126623619bc07abe826f/cc/paint/paint_shader.cc

ClusterFuzz has detected this issue as fixed in range 500422:500485.

Detailed report: https://clusterfuzz.com/testcase?key=6538222804140032

Fuzzer: libFuzzer_paint_op_buffer_fuzzer
Job Type: libfuzzer_chrome_asan_debug
Platform Id: linux

Crash Type: Abrt
Crash Address: 0x03e900003fb3
Crash State:
  sk_abort_no_print
  SkSweepGradient::SkSweepGradient
  sk_sp<SkSweepGradient> sk_make_sp<SkSweepGradient, SkPoint, float const&, float 
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan_debug&range=496919:496954
Fixed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan_debug&range=500422:500485

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6538222804140032

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 6538222804140032 is verified as fixed, so closing issue as verified.

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