This appears to have been fixed by 89f237cedcb8204f2c5553673669f55a41a9e2d9 (revision 12787), the fix for  bug 603498 .

ClusterFuzz has detected this issue as fixed in range 394410:394495.

Detailed report: https://cluster-fuzz.appspot.com/testcase?key=6605643804311552

Fuzzer: libfuzzer_audio_decoder_isac_fuzzer
Job Type: libfuzzer_chrome_ubsan
Platform Id: linux

Crash Type: Undefined-shift
Crash Address: 
Crash State:
  FindInvArSpec
  WebRtcIsac_DecodeSpec
  WebRtcIsac_DecodeLb
  
Regressed: https://cluster-fuzz.appspot.com/revisions?job=libfuzzer_chrome_ubsan&range=386932:386961
Fixed: https://cluster-fuzz.appspot.com/revisions?job=libfuzzer_chrome_ubsan&range=394410:394495

Minimized Testcase (6.25 Kb): https://cluster-fuzz.appspot.com/download/AMIfv97jT2nNfAHoWqwRjSI9ysbfQgHMAy_cmqjQCRcp8xLVlNzdLWymV9l1FDgfcSoK2HlD9vjShT6sDI31kXKR2o6ECRgJkF3DAIIyOnImnQDnSNamZe8xv9D2yLklI6ilkzskcVSLCXV0WdE7iAIJNGLeiiKeaA

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.

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