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[draft] Integrate native go fuzzing (#7055)
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AdamKorcz authored Feb 8, 2022
1 parent 74e61c2 commit 4fdde05
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44 changes: 40 additions & 4 deletions docs/getting-started/new-project-guide/go_lang.md
Original file line number Diff line number Diff line change
Expand Up @@ -27,10 +27,47 @@ only. In that mode, fuzz targets for Go use the libFuzzer engine with native Go
coverage instrumentation. Binaries compiled in this mode provide the same
libFuzzer command line interface as non-Go fuzz targets.

## Native Go Fuzzing support

OSS-fuzz supports fuzzers written for the native Go 1.18 engine. These fuzzers are built as libFuzzer binaries in a similar fashion as fuzzers written for the go-fuzz engine. Because of that, dictionaries and seed corpora should be handled in accordance with [the OSS-fuzz documentation](https://google.github.io/oss-fuzz/getting-started/new-project-guide/#seed-corpus).
Unlike libFuzzer/go-fuzz targets which must accept one data buffer, fuzz targets written for the Native Go engine can accept any number of arguments of any type. Here is an example of a valid fuzzer with multiple arguments:

```go
package demofuzzing

import (
"fmt"
"testing"
)

func FuzzDemo(f *testing.F) {
f.Fuzz(func(t *testing.T, data1 string, data2 uint32, data3 float64) {
fmt.Println(data1)
fmt.Println(data2)
fmt.Println(data3)
})
}
```

Some requirements for native Go 1.18 fuzzers are:
* The only `testing.F` method supported is currently `F.Fuzz()`.
* `F.Add()` will not add seeds when fuzzing. To provide OSS-fuzz with a seed corpus, follow the documentation [here](https://google.github.io/oss-fuzz/getting-started/new-project-guide/#seed-corpus).

### Troubleshooting
```console
main.1320908145.go:8:2: found packages nativefuzzing fuzzer_test.go_fuzz_.go) and main (main.1320908145.go) in /src/project/go/test/fuzzing/nativefuzzing
```

This issue occurs because the cwd is a directory with a non-main package when running `compile_native_go_fuzzer`. To solve it, create a temporary directory in your project tree and `cd` into it before running `compile_native_go_fuzzer`:

```sh
mkdir tmp && cd tmp
compile_native_go_fuzzer $path $fuzz_function $binary_name
```

## Project files

First, you need to write a Go fuzz target that accepts a stream of bytes and
calls the program API with that. This fuzz target should reside in your project
First, you need to write a Go fuzz target. This fuzz target should reside in your project
repository
([example](https://github.com/golang/go/blob/4ad13555184eb0697c2e92c64c1b0bdb287ccc10/src/html/fuzz.go#L13)).

Expand Down Expand Up @@ -79,8 +116,7 @@ In order to build a Go fuzz target, you need to call `go-fuzz`
command first, and then link the resulting `.a` file against
`$LIB_FUZZING_ENGINE` using the `$CXX $CXXFLAGS ...` command.

The best way to do this is by using a `compile_go_fuzzer` script,
as it also supports coverage builds.
For go-fuzz fuzzers, the best way to do this is by using the `compile_go_fuzzer` script, and for native Go 1.18 fuzzers it is recommended to use the `compile_native_go_fuzzer` script. Both of these also support coverage builds.

A usage example from go-dns project is

Expand Down
5 changes: 3 additions & 2 deletions infra/base-images/base-builder-go/Dockerfile
Original file line number Diff line number Diff line change
Expand Up @@ -26,5 +26,6 @@ ENV PATH $PATH:/root/.go/bin:$GOPATH/bin
RUN install_go.sh

# TODO(jonathanmetzman): Install this file using install_go.sh.
COPY ossfuzz_coverage_runner.go $GOPATH

COPY ossfuzz_coverage_runner.go \
native_ossfuzz_coverage_runner.go \
$GOPATH/
Original file line number Diff line number Diff line change
@@ -0,0 +1,71 @@
// Copyright 2022 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package mypackagebeingfuzzed

import (
"io/ioutil"
"os"
"runtime/pprof"
"testing"
"github.com/AdamKorcz/go-118-fuzz-build/utils"
)

func TestFuzzCorpus(t *testing.T) {
dir := os.Getenv("FUZZ_CORPUS_DIR")
if dir == "" {
t.Logf("No fuzzing corpus directory set")
return
}
infos, err := ioutil.ReadDir(dir)
if err != nil {
t.Logf("Not fuzzing corpus directory %s", err)
return
}
filename := ""
defer func() {
if r := recover(); r != nil {
t.Error("Fuzz panicked in "+filename, r)
}
}()
profname := os.Getenv("FUZZ_PROFILE_NAME")
if profname != "" {
f, err := os.Create(profname + ".cpu.prof")
if err != nil {
t.Logf("error creating profile file %s\n", err)
} else {
_ = pprof.StartCPUProfile(f)
}
}
for i := range infos {
filename = dir + infos[i].Name()
data, err := ioutil.ReadFile(filename)
if err != nil {
t.Error("Failed to read corpus file", err)
}
fuzzerF := &utils.F{Data:data, T:&testing.T{}}
FuzzFunction(fuzzerF)
}
if profname != "" {
pprof.StopCPUProfile()
f, err := os.Create(profname + ".heap.prof")
if err != nil {
t.Logf("error creating heap profile file %s\n", err)
}
if err = pprof.WriteHeapProfile(f); err != nil {
t.Logf("error writing heap profile file %s\n", err)
}
f.Close()
}
}
4 changes: 3 additions & 1 deletion infra/base-images/base-builder/Dockerfile
Original file line number Diff line number Diff line change
Expand Up @@ -146,7 +146,9 @@ COPY precompile_honggfuzz /usr/local/bin/
RUN precompile_honggfuzz

COPY cargo compile compile_afl compile_dataflow compile_libfuzzer compile_honggfuzz \
compile_go_fuzzer debug_afl srcmap \
compile_go_fuzzer \
compile_native_go_fuzzer \
debug_afl srcmap \
write_labels.py bazel_build_fuzz_tests \
# Go, java, and swift installation scripts.
install_go.sh \
Expand Down
97 changes: 97 additions & 0 deletions infra/base-images/base-builder/compile_native_go_fuzzer
Original file line number Diff line number Diff line change
@@ -0,0 +1,97 @@
#!/bin/bash -eu
# Copyright 2022 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
################################################################################

# Rewrites a copy of the fuzzer to allow for
# libFuzzer instrumentation.
function rewrite_go_fuzz_harness() {
fuzzer_filename=$1
fuzz_function=$2

# Create a copy of the fuzzer to not modify the existing fuzzer.
cp $fuzzer_filename "${fuzzer_filename}"_fuzz_.go
mv $fuzzer_filename /tmp/
fuzzer_fn="${fuzzer_filename}"_fuzz_.go

# Replace *testing.F with *go118fuzzbuildutils.F.
echo "replacing *testing.F"
sed -i "s/func $fuzz_function(\([a-zA-Z0-9]*\) \*testing\.F)/func $fuzz_function(\1 \*go118fuzzbuildutils\.F)/g" "${fuzzer_fn}"

# Import https://github.com/AdamKorcz/go-118-fuzz-build.
# This changes the line numbers from the original fuzzer.
addimport -path "${fuzzer_fn}"
}

function build_native_go_fuzzer() {
fuzzer=$1
function=$2
path=$3
tags="-tags gofuzz"

if [[ $SANITIZER = *coverage* ]]; then
echo "here we perform coverage build"
fuzzed_package=`go list $tags -f '{{.Name}}' $path`
abspath=`go list $tags -f {{.Dir}} $path`
cd $abspath
cp $GOPATH/native_ossfuzz_coverage_runner.go ./"${function,,}"_test.go
sed -i -e 's/FuzzFunction/'$function'/' ./"${function,,}"_test.go
sed -i -e 's/mypackagebeingfuzzed/'$fuzzed_package'/' ./"${function,,}"_test.go
sed -i -e 's/TestFuzzCorpus/Test'$function'Corpus/' ./"${function,,}"_test.go

# The repo is the module path/name, which is already created above
# in case it doesn't exist, but not always the same as the module
# path. This is necessary to handle SIV properly.
fuzzed_repo=$(go list $tags -f {{.Module}} "$path")
abspath_repo=`go list -m $tags -f {{.Dir}} $fuzzed_repo || go list $tags -f {{.Dir}} $fuzzed_repo`
# give equivalence to absolute paths in another file, as go test -cover uses golangish pkg.Dir
echo "s=$fuzzed_repo"="$abspath_repo"= > $OUT/$fuzzer.gocovpath
gotip test -run Test${function}Corpus -v $tags -coverpkg $fuzzed_repo/... -c -o $OUT/$fuzzer $path

rm ./"${function,,}"_test.go
else
go-118-fuzz-build -o $fuzzer.a -func $function $abs_file_dir
$CXX $CXXFLAGS $LIB_FUZZING_ENGINE $fuzzer.a -o $OUT/$fuzzer
fi
}


path=$1
function=$2
fuzzer=$3
tags="-tags gofuzz"

# Get absolute path.
abs_file_dir=$(go list $tags -f {{.Dir}} $path)

# TODO(adamkorcz): Get rid of "-r" flag here.
fuzzer_filename=$(grep -r -l -s "$function" "${abs_file_dir}")

# Test if file contains a line with "func $function" and "testing.F".
if [ $(grep -r "func $function" $fuzzer_filename | grep "testing.F" | wc -l) -eq 1 ]
then
# Install more dependencies.
gotip get github.com/AdamKorcz/go-118-fuzz-build/utils
gotip get google.golang.org/grpc/internal/[email protected]

rewrite_go_fuzz_harness $fuzzer_filename $function
build_native_go_fuzzer $fuzzer $function $abs_file_dir

# Clean up.
rm "${fuzzer_filename}_fuzz_.go"
mv /tmp/$(basename $fuzzer_filename) $fuzzer_filename
else
echo "Could not find the function: func ${function}(f *testing.F)"
fi
13 changes: 13 additions & 0 deletions infra/base-images/base-builder/install_go.sh
Original file line number Diff line number Diff line change
Expand Up @@ -26,3 +26,16 @@ echo 'Set "PATH=$PATH:/root/.go/bin:$GOPATH/bin"'

go get -u github.com/mdempsky/go114-fuzz-build
ln -s $GOPATH/bin/go114-fuzz-build $GOPATH/bin/go-fuzz

go install golang.org/dl/gotip@latest \
&& gotip download

cd /tmp
git clone https://github.com/AdamKorcz/go-118-fuzz-build
cd go-118-fuzz-build
gotip build
mv go-118-fuzz-build $GOPATH/bin/

cd addimport
gotip build
mv addimport $GOPATH/bin/
12 changes: 11 additions & 1 deletion infra/base-images/base-runner/coverage
Original file line number Diff line number Diff line change
Expand Up @@ -133,7 +133,15 @@ function run_go_fuzz_target {
echo "Running go target $target"
export FUZZ_CORPUS_DIR="$CORPUS_DIR/${target}/"
export FUZZ_PROFILE_NAME="$DUMPS_DIR/$target.perf"

$OUT/$target -test.coverprofile $DUMPS_DIR/$target.profdata &> $LOGS_DIR/$target.log

# The Go 1.18 fuzzers are renamed to "*_fuzz_.go" during "infra/helper.py build_fuzzers".
# They are are therefore refered to as "*_fuzz_.go" in the profdata files.
# Since the copies named "*_fuzz_.go" do not exist in the file tree during
# the coverage build, we change the references in the .profdata files
# to the original file names.
sed -i "s/_test.go_fuzz_.go/_test.go/g" $DUMPS_DIR/$target.profdata
# translate from golangish paths to current absolute paths
cat $OUT/$target.gocovpath | while read i; do sed -i $i $DUMPS_DIR/$target.profdata; done
# cf PATH_EQUIVALENCE_ARGS
Expand Down Expand Up @@ -231,7 +239,9 @@ wait

if [[ $FUZZING_LANGUAGE == "go" ]]; then
$SYSGOPATH/bin/gocovmerge $DUMPS_DIR/*.profdata > fuzz.cov
go tool cover -html=fuzz.cov -o $REPORT_ROOT_DIR/index.html
# TODO(adamkorcz): Once oss-fuzz upgrades go to 1.18,
# use "go" instead of "gotip":
gotip tool cover -html=fuzz.cov -o $REPORT_ROOT_DIR/index.html
$SYSGOPATH/bin/gocovsum fuzz.cov > $SUMMARY_FILE
cp $REPORT_ROOT_DIR/index.html $REPORT_PLATFORM_DIR/index.html
$SYSGOPATH/bin/pprof-merge $DUMPS_DIR/*.perf.cpu.prof
Expand Down

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