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.

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The regression range is suspect, containing only one CL for QUIC code cleanup.

Xianzhu, could you please take a look as per https://chromium.googlesource.com/chromium/src/+/562876f283093f8facece42cafa3defde3d5e000 and https://chromium.googlesource.com/chromium/src/+/ac1414588aedb11ae6a11223c7c3cca1057a4773

Added "Test-Predator-Wrong-CLs" as per c#4.

Encountered DCHECK with dcheck_always_on by running:
out/release/chrome --js-flags="--expose-gc --verify-heap" --user-data-dir=/tmp/clusterfuzz-user-data-dir test-case.html

    DCHECK(cached_item->Client().IsAlive());
in PaintController::CopyCachedSubsequence().

This is an under-invalidation of subsequence.

Not spv175 specific.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/af3e961ab018262a08de4b9c73e1ddeefce7160f

commit af3e961ab018262a08de4b9c73e1ddeefce7160f
Author: Xianzhu Wang <wangxianzhu@chromium.org>
Date: Wed Apr 04 21:44:32 2018

[PE] Invalidate parent layer for non-self-painting layer having self-painting descendants

For a non-self-painting layer having self-painting descendants, the
non-stacked layers are painted through the non-self-painting layer's
parent, which may be different from the non-self-painting layer's
container through which the non-self-painting layer is painted. We
need to invalidate both path to ensure correct subsequence caching.

Bug:  826659 
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: Ic0d0745a50f34b7b7e23da226e62e8599de68aa5
Reviewed-on: https://chromium-review.googlesource.com/990718
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548211}
[modify] https://crrev.com/af3e961ab018262a08de4b9c73e1ddeefce7160f/third_party/WebKit/Source/core/paint/PaintLayer.cpp
[modify] https://crrev.com/af3e961ab018262a08de4b9c73e1ddeefce7160f/third_party/WebKit/Source/core/paint/PaintLayerTest.cpp

ClusterFuzz has detected this issue as fixed in range 548205:548215.

Detailed report: https://clusterfuzz.com/testcase?key=6244117483618304

Fuzzer: ochang_domfuzzer
Job Type: linux_asan_chrome_mp
Platform Id: linux

Crash Type: Heap-use-after-free READ 4
Crash Address: 0x608000047da8
Crash State:
  blink::PaintController::GenerateRasterInvalidationsComparingChunks
  blink::PaintController::GenerateRasterInvalidations
  blink::PaintController::CommitNewDisplayItems
  
Sanitizer: address (ASAN)

Recommended Security Severity: High

Regressed: https://clusterfuzz.com/revisions?job=linux_asan_chrome_mp&range=537481:537482
Fixed: https://clusterfuzz.com/revisions?job=linux_asan_chrome_mp&range=548205:548215

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6244117483618304

See https://github.com/google/clusterfuzz-tools 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 6244117483618304 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