Looks like the culprit CL was already reverted, but adding chongz to confirm, please.

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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Confirm that it was caused by my CL and reverting it should have fixed the issue.

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The root cause seems to be that I have an initialized var A and un-initialized var B. I copied value from B to A, and A was then caught by MSAN.

ClusterFuzz has detected this issue as fixed in range 480271:480453.

Detailed report: https://clusterfuzz.com/testcase?key=4831661429882880

Fuzzer: inferno_twister
Job Type: linux_msan_content_shell_drt
Platform Id: linux

Crash Type: Use-of-uninitialized-value
Crash Address: 
Crash State:
  base::Pickle::WriteData
  IPC::ParamTraits<std::__1::tuple<blink::WebInputEvent const* const&, std::__1::v
  IPC::MessageT<InputMsg_HandleInputEvent_Meta, std::__1::tuple<blink::WebInputEve
  
Sanitizer: memory (MSAN)

Recommended Security Severity: Medium

Regressed: https://clusterfuzz.com/revisions?job=linux_msan_content_shell_drt&range=480110:480214
Fixed: https://clusterfuzz.com/revisions?job=linux_msan_content_shell_drt&range=480271:480453

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=4831661429882880


See https://dev.chromium.org/Home/chromium-security/bugs/reproducing-clusterfuzz-bugs for more information.

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.

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