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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WebRTC roll in this range is https://chromium.googlesource.com/chromium/src/+/340c463f86e06b293061e33e14acb17b77ffbc86

I don't understand what's uninitialized in the failure (the rtcp_packet_transport is defaulted to a nullptr in the header).

The CL https://webrtc.googlesource.com/src.git/+/27f3bf512827b483f9e0c67ce76362d83faa1950 is in the regression range and did touch the file in question, so perhaps it's related somehow.

Very likely a duplicate of 826725, as UIM under MSan is often UaF under ASan.

ClusterFuzz has detected this issue as fixed in range 546863:546887.

Detailed report: https://clusterfuzz.com/testcase?key=5940375383179264

Fuzzer: phoglund_webrtc_peerconnection
Job Type: linux_msan_chrome
Platform Id: linux

Crash Type: Use-of-uninitialized-value
Crash Address: 
Crash State:
  webrtc::RtpTransport::OnWritableState
  cricket::DtlsTransport::set_writable
  cricket::DtlsTransport::OnDtlsEvent
  
Sanitizer: memory (MSAN)

Recommended Security Severity: Medium

Regressed: https://clusterfuzz.com/revisions?job=linux_msan_chrome&range=546383:546390
Fixed: https://clusterfuzz.com/revisions?job=linux_msan_chrome&range=546863:546887

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=5940375383179264

Additional requirements: Requires HTTP

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 5940375383179264 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