From: Andrzej Hunt <ajrhunt@xxxxxxxxxx> Clang no longer produces a libFuzzer.a, instead you can include libFuzzer by using -fsanitize=fuzzer. Therefore we should use that in the example command for building fuzzers. We also add -fsanitize=fuzzer-no-link to ensure that all the required instrumentation is added when compiling git [1], and remove -fsanitize-coverage=trace-pc-guard as it is deprecated. I happen to have tested with LLVM 11 - however -fsanitize=fuzzer appears to work in a wide range of reasonably modern clangs. (On my system: what used to be libFuzzer.a now lives under the following path, which is tricky albeit not impossible for a novice such as myself to find: /usr/lib64/clang/11.0.0/lib/linux/libclang_rt.fuzzer-x86_64.a ) [1] https://releases.llvm.org/11.0.0/docs/LibFuzzer.html#fuzzer-usage Signed-off-by: Andrzej Hunt <ajrhunt@xxxxxxxxxx> --- Update 'make fuzz-all' docs to reflect modern clang I have updated my patch to: * Remove -fsanitize-coverage=trace-pc-guard as it is deprecated. * Add -fsanitize=fuzzer-no-link as per Josh's suggestion. Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-889%2Fahunt%2Ffuzz-docs-v2 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-889/ahunt/fuzz-docs-v2 Pull-Request: https://github.com/gitgitgadget/git/pull/889 Range-diff vs v1: 1: d804b24907fd ! 1: f5b5a11966ca Update 'make fuzz-all' docs to reflect modern clang @@ Commit message libFuzzer by using -fsanitize=fuzzer. Therefore we should use that in the example command for building fuzzers. + We also add -fsanitize=fuzzer-no-link to ensure that all the required + instrumentation is added when compiling git [1], and remove + -fsanitize-coverage=trace-pc-guard as it is deprecated. + I happen to have tested with LLVM 11 - however -fsanitize=fuzzer appears to work in a wide range of reasonably modern clangs. - (On my system what used to be libFuzzer.a now lives under the following path, + (On my system: what used to be libFuzzer.a now lives under the following path, which is tricky albeit not impossible for a novice such as myself to find: /usr/lib64/clang/11.0.0/lib/linux/libclang_rt.fuzzer-x86_64.a ) + [1] https://releases.llvm.org/11.0.0/docs/LibFuzzer.html#fuzzer-usage + Signed-off-by: Andrzej Hunt <ajrhunt@xxxxxxxxxx> ## Makefile ## @@ Makefile: cover_db_html: cover_db +# An example command to build against libFuzzer from LLVM 11.0.0: # # make CC=clang CXX=clang++ \ - # CFLAGS="-fsanitize-coverage=trace-pc-guard -fsanitize=address" \ +-# CFLAGS="-fsanitize-coverage=trace-pc-guard -fsanitize=address" \ -# LIB_FUZZING_ENGINE=/usr/lib/llvm-4.0/lib/libFuzzer.a \ -+# LIB_FUZZING_ENGINE=-fsanitize=fuzzer \ ++# CFLAGS="-fsanitize=fuzzer-no-link,address" \ ++# LIB_FUZZING_ENGINE="-fsanitize=fuzzer" \ # fuzz-all # FUZZ_CXXFLAGS ?= $(CFLAGS) Makefile | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/Makefile b/Makefile index dd08b4ced01c..c7248ac6057b 100644 --- a/Makefile +++ b/Makefile @@ -3292,11 +3292,11 @@ cover_db_html: cover_db # are not necessarily appropriate for general builds, and that vary greatly # depending on the compiler version used. # -# An example command to build against libFuzzer from LLVM 4.0.0: +# An example command to build against libFuzzer from LLVM 11.0.0: # # make CC=clang CXX=clang++ \ -# CFLAGS="-fsanitize-coverage=trace-pc-guard -fsanitize=address" \ -# LIB_FUZZING_ENGINE=/usr/lib/llvm-4.0/lib/libFuzzer.a \ +# CFLAGS="-fsanitize=fuzzer-no-link,address" \ +# LIB_FUZZING_ENGINE="-fsanitize=fuzzer" \ # fuzz-all # FUZZ_CXXFLAGS ?= $(CFLAGS) base-commit: f01623b2c9d14207e497b21ebc6b3ec4afaf4b46 -- gitgitgadget
