Automatically applying components based on crash stacktrace and information from OWNERS files.

If this is incorrect, please apply the Test-Predator-Wrong-Components label.

Automatically assigning owner based on suspected regression changelist https://chromium.googlesource.com/v8/v8/+/829670e16ab9761dc03d613e07d3e27385b7ab46 ([wasm] Canonicalize signatures per module at module decode time.).

If this is incorrect, please remove the owner and apply the Test-Predator-Wrong-CLs label.

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/b2199faf52fe4b9e5f969e7d920f4fabf4887b43

commit b2199faf52fe4b9e5f969e7d920f4fabf4887b43
Author: Ben L. Titzer <titzer@chromium.org>
Date: Fri Oct 20 14:00:34 2017

g# Enter a description of the change.
[wasm] Fix signature canonicalization for error case.

The decoder should not attempt to insert null signatures into the SignatureMap.

R=ahaas@chromium.org

Bug:  chromium:775366 
Change-Id: I0fbc0547dbf00fd25d37271a03b6756481a4c6a1
Reviewed-on: https://chromium-review.googlesource.com/730752
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48793}
[modify] https://crrev.com/b2199faf52fe4b9e5f969e7d920f4fabf4887b43/src/wasm/module-decoder.cc
[add] https://crrev.com/b2199faf52fe4b9e5f969e7d920f4fabf4887b43/test/mjsunit/regress/wasm/regress-775366.js

ClusterFuzz has detected this issue as fixed in range 510629:510646.

Detailed report: https://clusterfuzz.com/testcase?key=6089218026897408

Fuzzer: libFuzzer_v8_wasm_types_section_fuzzer
Job Type: libfuzzer_chrome_asan
Platform Id: linux

Crash Type: Null-dereference READ
Crash Address: 0x000000000000
Crash State:
  v8::internal::Signature<v8::internal::MachineRepresentation>::return_count
  v8::internal::wasm::SignatureMap::CompareFunctionSigs::operator
  v8::internal::wasm::SignatureMap::FindOrInsert
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan&range=509183:509189
Fixed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan&range=510629:510646

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6089218026897408

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 6089218026897408 is verified as fixed, so closing issue as verified.

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