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Merge #15043: test: Build fuzz targets into seperate executables

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2ca632e5b4 test: Build fuzz targets into seperate executables (MarcoFalke)
fab4bed68a [test] fuzz: make test_one_input return void (MarcoFalke)

Pull request description:

  Currently our fuzzer is a single binary that decides on the first few bits of the buffer what target to pick. This is ineffective as the fuzzer needs to "learn" how the fuzz targets are organized and could get easily confused. Not to mention that the (seed) corpus can not be categorized by target, since targets might "leak" into each other. Also the corpus would potentially become invalid if we ever wanted to remove a target...

  Solve that by building each fuzz target into their own executable.

Tree-SHA512: a874febc85a3c5e6729199542b65cad10640553fba6f663600c827fe144543744dd0f844fb62b4c95c6a04c670bfce32cdff3d5f26de2dfc25f10b258eda18ab
This commit is contained in:
Wladimir J. van der Laan
2019-01-30 21:09:39 +01:00
parent 77339e5c24 2ca632e5b4
commit 9553102c38
7 changed files with 528 additions and 240 deletions
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16
doc/fuzzing.md
View File

@@ -1,9 +1,9 @@
Fuzz-testing Bitcoin Core
==========================
A special test harness `test_bitcoin_fuzzy` is provided to provide an easy
entry point for fuzzers and the like. In this document we'll describe how to
use it with AFL and libFuzzer.
A special test harness in `src/test/fuzz/` is provided for each fuzz target to
provide an easy entry point for fuzzers and the like. In this document we'll
describe how to use it with AFL and libFuzzer.
## AFL
@@ -23,10 +23,10 @@ export AFLPATH=$PWD
To build Bitcoin Core using AFL instrumentation (this assumes that the
`AFLPATH` was set as above):
```
./configure --disable-ccache --disable-shared --enable-tests CC=${AFLPATH}/afl-gcc CXX=${AFLPATH}/afl-g++
./configure --disable-ccache --disable-shared --enable-tests --enable-fuzz CC=${AFLPATH}/afl-gcc CXX=${AFLPATH}/afl-g++
export AFL_HARDEN=1
cd src/
make test/test_bitcoin_fuzzy
make
```
We disable ccache because we don't want to pollute the ccache with instrumented
objects, and similarly don't want to use non-instrumented cached objects linked
@@ -35,7 +35,7 @@ in.
The fuzzing can be sped up significantly (~200x) by using `afl-clang-fast` and
`afl-clang-fast++` in place of `afl-gcc` and `afl-g++` when compiling. When
compiling using `afl-clang-fast`/`afl-clang-fast++` the resulting
`test_bitcoin_fuzzy` binary will be instrumented in such a way that the AFL
binary will be instrumented in such a way that the AFL
features "persistent mode" and "deferred forkserver" can be used. See
https://github.com/mcarpenter/afl/tree/master/llvm_mode for details.
@@ -63,7 +63,7 @@ Extract these (or other starting inputs) into the `inputs` directory before star
To start the actual fuzzing use:
```
$AFLPATH/afl-fuzz -i ${AFLIN} -o ${AFLOUT} -m52 -- test/test_bitcoin_fuzzy
$AFLPATH/afl-fuzz -i ${AFLIN} -o ${AFLOUT} -m52 -- test/fuzz/fuzz_target_foo
```
You may have to change a few kernel parameters to test optimally - `afl-fuzz`
@@ -77,7 +77,7 @@ found in the `compiler-rt` runtime libraries package).
To build the `test/test_bitcoin_fuzzy` executable run
```
./configure --disable-ccache --with-sanitizers=fuzzer,address CC=clang CXX=clang++
./configure --disable-ccache --enable-fuzz --with-sanitizers=fuzzer,address CC=clang CXX=clang++
make
```