After discussion with Andreas this seems to be related to my change where I removed the "maximum memory size" from the WasmModuleBuilder, not realizing that the fuzzer also uses the module builder. Will cook up a fix. Thanks Andreas, good catch!

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/94b521126b869ddfec755c79f4edbd845c368c21

commit 94b521126b869ddfec755c79f4edbd845c368c21
Author: Michael Starzinger <mstarzinger@chromium.org>
Date: Tue Aug 29 11:33:07 2017

[wasm] Support max memory size in WasmModuleBuilder.

This adds support to specify the maximum memory size when building a
WebAssembly module. Default is not maximum, one can be explicitly set.
It is mainly used by the WebAssembly fuzzers to prevent OOMs.

R=ahaas@chromium.org
BUG= chromium:759973 

Change-Id: Ibf5fa63a7e36e5f3b65ced528c73a65355d5632f
Reviewed-on: https://chromium-review.googlesource.com/640386
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47676}
[modify] https://crrev.com/94b521126b869ddfec755c79f4edbd845c368c21/src/wasm/wasm-module-builder.cc
[modify] https://crrev.com/94b521126b869ddfec755c79f4edbd845c368c21/src/wasm/wasm-module-builder.h
[modify] https://crrev.com/94b521126b869ddfec755c79f4edbd845c368c21/test/fuzzer/wasm-call.cc
[modify] https://crrev.com/94b521126b869ddfec755c79f4edbd845c368c21/test/fuzzer/wasm-code.cc
[modify] https://crrev.com/94b521126b869ddfec755c79f4edbd845c368c21/test/fuzzer/wasm-compile.cc

Should be fixed by change in comment #4, leaving issue open and waiting for ClusterFuzz to confirm though.

ClusterFuzz has detected this issue as fixed in range 498116:498178.

Detailed report: https://clusterfuzz.com/testcase?key=5683371572461568

Fuzzer: libFuzzer_v8_wasm_code_fuzzer
Job Type: libfuzzer_chrome_asan_debug
Platform Id: linux

Crash Type: Out-of-memory (exceeds 2048 MB)
Crash Address: 
Crash State:
  v8_wasm_code_fuzzer
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan_debug&range=497803:497860
Fixed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan_debug&range=498116:498178

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=5683371572461568

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.

Yep, fixed.

ClusterFuzz testcase 5683371572461568 is verified as fixed, so closing issue as verified.

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