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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fdoray, could this have been caused by https://chromium.googlesource.com/chromium/src/+/a2d01bae3fbe6fd4c6433ef1163350d25945b298 ?

yes, fixing this in on my TODO list

ClusterFuzz has detected this issue as fixed in range 509032:509158.

Detailed report: https://clusterfuzz.com/testcase?key=6129151760400384

Fuzzer: libFuzzer_net_host_resolver_impl_fuzzer
Job Type: mac_libfuzzer_chrome_asan
Platform Id: mac

Crash Type: Heap-buffer-overflow READ 1
Crash Address: 0x60700002b3cf
Crash State:
  base::BasicStringPiece<std::__1::basic_string<char, std::__1::char_traits<char>,
  net::FuzzedHostResolverProc::Resolve
  net::HostResolverImpl::ProcTask::DoLookup
  
Sanitizer: address (ASAN)

Recommended Security Severity: Medium

Regressed: https://clusterfuzz.com/revisions?job=mac_libfuzzer_chrome_asan&range=504079:504126
Fixed: https://clusterfuzz.com/revisions?job=mac_libfuzzer_chrome_asan&range=509032:509158

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6129151760400384

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 6129151760400384 is verified as fixed, so closing issue as verified.

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

fdoray@ - is there a fix we should be looking to merge to M63?

Hi mgersh@ - Might this be related to your "Fix threading in HostResolverImpl fuzzer" change?

Yes, it has the same cause as  issue 769235 , which was fixed by that CL. No need to merge anything, the bug was in the fuzzer itself.

thanks mgersh@!

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