Predator and CL could not provide any possible suspects.
Using Code Search for the file, "CSSVariableParser.cpp" assigning to the concern owner.

Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/a3079e2f1ea9974caebcdebd00c1c33dbaa662e0

@alancutter -- Could you please look into it issue, kindly re-assign if this not related your changes.
Thank You.

Could anyone from Blink>CSS team please take a look and update the thread as this is a blocker issue & owner (meade@) is OOO till Oct 3rd-2017.

Thanks..!!

Unassigning meade@ as they are OOO.

The test case is just heaps of unclosed open brackets, causing a stack overflow in this recursive call: https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/css/parser/CSSVariableParser.cpp?q=ClassifyBlock&sq=package:chromium&l=41

We could make this non-recursive, but this seems like a weird artificial case that won't appear in real world websites. Removing ReleaseBlock-Beta label.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/654ffec610219dad73aca9c5fc7c8fd666af7551

commit 654ffec610219dad73aca9c5fc7c8fd666af7551
Author: Darren Shen <shend@chromium.org>
Date: Mon Sep 25 10:55:19 2017

Remove recursive calls from ClassifyBlock to prevent stack overflows.

This patch changes ClassifyBlock to be iterative rather than recursive
so we don't get stack overflows when the nesting level gets too big.
To remove the recursion, we handle each token one by one, keeping track
of the nesting level in an integer.

Bug:  763219 
Change-Id: I7567e51bf41a68806686e4e5342ea34984d53b59
Reviewed-on: https://chromium-review.googlesource.com/680197
Reviewed-by: nainar <nainar@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#504027}
[add] https://crrev.com/654ffec610219dad73aca9c5fc7c8fd666af7551/third_party/WebKit/LayoutTests/css-parser/unclosed-open-brackets-crash.html
[modify] https://crrev.com/654ffec610219dad73aca9c5fc7c8fd666af7551/third_party/WebKit/Source/core/css/parser/CSSVariableParser.cpp

ClusterFuzz has detected this issue as fixed in range 503967:504119.

Detailed report: https://clusterfuzz.com/testcase?key=5057785707626496

Fuzzer: inferno_twister
Job Type: linux_asan_content_shell_drt
Platform Id: linux

Crash Type: Stack-overflow
Crash Address: 0x7ffdb140f840
Crash State:
  blink::ClassifyBlock
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=linux_asan_content_shell_drt&range=496937:496959
Fixed: https://clusterfuzz.com/revisions?job=linux_asan_content_shell_drt&range=503967:504119

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=5057785707626496

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 5057785707626496 is verified as fixed, so closing issue as verified.

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