Since 5e47215080 (fuzz: add basic fuzz testing target., 2018-10-12), we
have compiled object files for the fuzz tests as part of the default
'make all' target. This helps prevent bit-rot in lesser-used parts of
the codebase, by making sure that incompatible changes are caught at
build time.
However, since we never linked the fuzzer executables, this did not
protect us from link-time errors. As of 8b9a42bf48 (fuzz: fix fuzz test
build rules, 2024-01-19), it's now possible to link the fuzzer
executables without using a fuzzing engine and a variety of
compiler-specific (and compiler-version-specific) flags, at least on
Linux. So let's add a platform-specific option in config.mak.uname to
link the executables as part of the default `make all` target.
Since linking the fuzzer executables without a fuzzing engine does not
require a C++ compiler, we can change the FUZZ_PROGRAMS build rule to
use $(CC) by default. This avoids compiler mis-match issues when
overriding $(CC) but not $(CXX). When we *do* want to actually link with
a fuzzing engine, we can set $(FUZZ_CXX). The build instructions in the
CI fuzz-smoke-test job and in the Makefile comment have been updated
accordingly.
While we're at it, we can consolidate some of the fuzzer build
instructions into one location in the Makefile.
Suggested-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a new fuzz target that exercises the parsing of git configs.
The existing git_config_from_mem function is a perfect entry point
for fuzzing as it exercises the same code paths as the rest of the
config parsing functions and offers an easily fuzzable interface.
Config parsing is a useful thing to fuzz because it operates on user
controlled data and is a central component of many git operations.
Signed-off-by: Brian C Tracy <brian.tracy33@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
To prevent bitrot, we would like to regularly exercise the fuzz tests in
order to make sure they still link & run properly. We already compile
the fuzz test objects as part of the default `make` target, but we do
not link the executables due to the fuzz tests needing specific
compilers and compiler features. This has lead to frequent build
breakages for the fuzz tests.
To remedy this, we can add a CI step to actually link the fuzz
executables, and run them (with finite input rather than the default
infinite random input mode) to verify that they execute properly.
Since the main use of the fuzz tests is via OSS-Fuzz [1], and OSS-Fuzz
only runs tests on Linux [2], we only set up a CI test for the fuzzers
on Linux.
[1] https://github.com/google/oss-fuzz
[2] https://google.github.io/oss-fuzz/further-reading/fuzzer-environment/
Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Josh Steadmon
Brian C Tracy