This is a serious security regression. If you are not able to fix this quickly, please revert the change that introduced it.

If this doesn't affect a release branch, or has not been properly classified for severity, please update the Security_Impact or Security_Severity labels, and remove the ReleaseBlock label. To disable this altogether, apply ReleaseBlock-NA.

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

bsalomon@ -- please help triage this bug. Thanks.

The following revision refers to this bug:
  https://skia.googlesource.com/skia/+/b3f6ac44dba7b8bc30c37753c7ce1257633525d6

commit b3f6ac44dba7b8bc30c37753c7ce1257633525d6
Author: Brian Salomon <bsalomon@google.com>
Date: Mon Jul 31 13:22:42 2017

Don't create GrAtlasTextBlobs for zero glyph count text draws.

Bug:  chromium:749472 

Change-Id: I709889dd6bb06032e30cbf820ca67e7534cfac58
Reviewed-on: https://skia-review.googlesource.com/28540
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

[modify] https://crrev.com/b3f6ac44dba7b8bc30c37753c7ce1257633525d6/src/gpu/text/GrAtlasTextContext.cpp

ClusterFuzz has detected this issue as fixed in range 490988:491060.

Detailed report: https://clusterfuzz.com/testcase?key=5331194639286272

Fuzzer: libFuzzer_paint_op_buffer_fuzzer
Job Type: libfuzzer_chrome_asan
Platform Id: linux

Crash Type: UNKNOWN READ
Crash Address: 0x630ffffffff4
Crash State:
  GrAtlasTextBlob::Run::SubRunInfo::maskFormat
  GrAtlasTextBlob::appendGlyph
  GrTextUtils::BmpAppendGlyph
  
Sanitizer: address (ASAN)

Recommended Security Severity: Medium

Regressed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan&range=489393:489475
Fixed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan&range=490988:491060

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=5331194639286272


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 4740882858508288 is verified as fixed, so closing issue as verified.

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

This bug has been closed for more than 14 weeks. Removing security view restrictions.

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