1806369 - Avoid cloning/building libFuzzer, use Clang's version instead

Status: RESOLVED FIXED

(NSS :: Build, enhancement)

Description

[Christian Holler (:decoder)]

It is generally not advisable to build libFuzzer yourself nowadays unless you have requirements that force you to (like mozilla-central requiring it for additional patches). The recommended way currently is to

• compile all source files with -fsanitize=fuzzer-no-link which will automatically pick whatever combination of instrumentation is required and recommended for libFuzzer and

• link with -fsanitize=fuzzer which will automatically link the libFuzzer runtime parts.

Doing so also ensures that the libFuzzer version matches the Clang version. Furthermore, newest libFuzzer builds now require the use of C++17, so it wouldn't even build in the NSS build system without further changes.

I have a patch to just use the libFuzzer version that ships with Clang. All of this only affects the non-oss fuzzing builds as oss-fuzz provides its own engine and configuration.

Keeping s-s until we have integrated all the recent fuzzing changes and made sure that everything runs smoothly on oss-fuzz.

Comment 1

[Christian Holler (:decoder)]

Attachment: Bug 1806369 - Don't clone libFuzzer, rely on clang instead. r?djackson,truber

Comment 2

[John Schanck [:jschanck]]

https://hg.mozilla.org/projects/nss/rev/0a3c0801ffb55a8df551a0503a3f51f7ef7a223b