fuzz: add oss-fuzz build-script

R: Stefan Hajnoczi <stefanha@redhat.com>

S: Maintained

F: tests/qtest/fuzz/

F: scripts/oss-fuzz/

Register API

M: Alistair Francis <alistair@alistair23.me>

#!/bin/sh -e

#

# OSS-Fuzz build script. See:

# https://google.github.io/oss-fuzz/getting-started/new-project-guide/#buildsh

#

# The file is consumed by:

# https://github.com/google/oss-fuzz/blob/master/projects/qemu/Dockerfiles

#

# This code is licensed under the GPL version 2 or later.  See

# the COPYING file in the top-level directory.

#

# build project

# e.g.

# ./autogen.sh

# ./configure

# make -j$(nproc) all

# build fuzzers

# e.g.

# $CXX $CXXFLAGS -std=c++11 -Iinclude \

#     /path/to/name_of_fuzzer.cc -o $OUT/name_of_fuzzer \

#     $LIB_FUZZING_ENGINE /path/to/library.a

fatal () {

    echo "Error : ${*}, exiting."

    exit 1

}

OSS_FUZZ_BUILD_DIR="./build-oss-fuzz/"

# There seems to be a bug in clang-11 (used for builds on oss-fuzz) :

#   accel/tcg/cputlb.o: In function `load_memop':

#   accel/tcg/cputlb.c:1505: undefined reference to `qemu_build_not_reached'

#

# When building with optimization, the compiler is expected to prove that the

# statement cannot be reached, and remove it. For some reason clang-11 doesn't

# remove it, resulting in an unresolved reference to qemu_build_not_reached

# Undefine the __OPTIMIZE__ macro which compiler.h relies on to choose whether

# to " #define qemu_build_not_reached()  g_assert_not_reached() "

EXTRA_CFLAGS="$CFLAGS -U __OPTIMIZE__"

if ! { [ -e "./COPYING" ] &&

   [ -e "./MAINTAINERS" ] &&

   [ -e "./Makefile" ] &&

   [ -e "./docs" ] &&

   [ -e "./VERSION" ] &&

   [ -e "./linux-user" ] &&

   [ -e "./softmmu" ];} ; then

    fatal "Please run the script from the top of the QEMU tree"

fi

mkdir -p $OSS_FUZZ_BUILD_DIR || fatal "mkdir $OSS_FUZZ_BUILD_DIR failed"

cd $OSS_FUZZ_BUILD_DIR || fatal "cd $OSS_FUZZ_BUILD_DIR failed"

if [ -z ${LIB_FUZZING_ENGINE+x} ]; then

    LIB_FUZZING_ENGINE="-fsanitize=fuzzer"

fi

if [ -z ${OUT+x} ]; then

    DEST_DIR=$(realpath "./DEST_DIR")

else

    DEST_DIR=$OUT

fi

mkdir -p "$DEST_DIR/lib/"  # Copy the shared libraries here

# Build once to get the list of dynamic lib paths, and copy them over

../configure --disable-werror --cc="$CC" --cxx="$CXX" \

    --extra-cflags="$EXTRA_CFLAGS"

if ! make CONFIG_FUZZ=y CFLAGS="$LIB_FUZZING_ENGINE" "-j$(nproc)" \

    i386-softmmu/fuzz; then

    fatal "Build failed. Please specify a compiler with fuzzing support"\

          "using the \$CC and \$CXX environemnt variables, or specify a"\

          "\$LIB_FUZZING_ENGINE compatible with your compiler"\

          "\nFor example: CC=clang CXX=clang++ $0"

fi

for i in $(ldd ./i386-softmmu/qemu-fuzz-i386 | cut -f3 -d' '); do

    cp "$i" "$DEST_DIR/lib/"

done

rm ./i386-softmmu/qemu-fuzz-i386

# Build a second time to build the final binary with correct rpath

../configure --bindir="$DEST_DIR" --datadir="$DEST_DIR/data/" --disable-werror \

    --cc="$CC" --cxx="$CXX" --extra-cflags="$EXTRA_CFLAGS" \

    --extra-ldflags="-Wl,-rpath,'\$\$ORIGIN/lib'"

make CONFIG_FUZZ=y CFLAGS="$LIB_FUZZING_ENGINE" "-j$(nproc)" i386-softmmu/fuzz

# Copy over the datadir

cp  -r ../pc-bios/ "$DEST_DIR/pc-bios"

# Run the fuzzer with no arguments, to print the help-string and get the list

# of available fuzz-targets. Copy over the qemu-fuzz-i386, naming it according

# to each available fuzz target (See 05509c8e6d fuzz: select fuzz target using

# executable name)

for target in $(./i386-softmmu/qemu-fuzz-i386 | awk '$1 ~ /\*/  {print $2}');

do

    cp ./i386-softmmu/qemu-fuzz-i386 "$DEST_DIR/qemu-fuzz-i386-target-$target"

done

echo "Done. The fuzzers are located in $DEST_DIR"

exit 0