qemu/scripts/oss-fuzz/build.sh
Alexander Bulekov f8b8f37463 scripts/oss-fuzz: rename bin/qemu-fuzz-i386
OSS-Fuzz changed the way it scans for fuzzers in $DEST_DIR. The new code
also scans subdirectories for fuzzers. This means that OSS-Fuzz is
considering bin/qemu-fuzz-i386 as an independent fuzzer (it is not - it
requires a --fuzz-target argument). This has led to coverage-build
failures and false crash reports. To work around this, we take advantage
of OSS-Fuzz' filename extension check - OSS-Fuzz will not run anything
that has an extension that is not ".exe":
https://github.com/google/oss-fuzz/blob/master/infra/utils.py#L115

Reported-by: OSS-Fuzz (Issue 26725)
Reported-by: OSS-Fuzz (Issue 26679)
Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Message-Id: <20201101212245.185819-1-alxndr@bu.edu>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-11-03 09:42:53 -05:00

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#!/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 \
# -fsanitize=fuzzer /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 ${OUT+x} ]; then
DEST_DIR=$(realpath "./DEST_DIR")
else
DEST_DIR=$OUT
fi
mkdir -p "$DEST_DIR/lib/" # Copy the shared libraries here
mkdir -p "$DEST_DIR/bin/" # Copy executables that shouldn't
# be treated as fuzzers by oss-fuzz here
# Build once to get the list of dynamic lib paths, and copy them over
../configure --disable-werror --cc="$CC" --cxx="$CXX" --enable-fuzzing \
--prefix="$DEST_DIR" --bindir="$DEST_DIR" --datadir="$DEST_DIR/data/" \
--extra-cflags="$EXTRA_CFLAGS" --target-list="i386-softmmu"
if ! make "-j$(nproc)" qemu-fuzz-i386; then
fatal "Build failed. Please specify a compiler with fuzzing support"\
"using the \$CC and \$CXX environment variables"\
"\nFor example: CC=clang CXX=clang++ $0"
fi
for i in $(ldd ./qemu-fuzz-i386 | cut -f3 -d' '); do
cp "$i" "$DEST_DIR/lib/"
done
rm qemu-fuzz-i386
# Build a second time to build the final binary with correct rpath
../configure --disable-werror --cc="$CC" --cxx="$CXX" --enable-fuzzing \
--prefix="$DEST_DIR" --bindir="$DEST_DIR" --datadir="$DEST_DIR/data/" \
--extra-cflags="$EXTRA_CFLAGS" --extra-ldflags="-Wl,-rpath,\$ORIGIN/lib" \
--target-list="i386-softmmu"
make "-j$(nproc)" qemu-fuzz-i386 V=1
# Copy over the datadir
cp -r ../pc-bios/ "$DEST_DIR/pc-bios"
cp "./qemu-fuzz-i386" "$DEST_DIR/bin/qemu-fuzz-i386.base"
# 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 $(./qemu-fuzz-i386 | awk '$1 ~ /\*/ {print $2}');
do
# Ignore the generic-fuzz target, as it requires some environment variables
# to be configured. We have some generic-fuzz-{pc-q35, floppy, ...} targets
# that are thin wrappers around this target that set the required
# environment variables according to predefined configs.
if [ "$target" != "generic-fuzz" ]; then
ln "$DEST_DIR/bin/qemu-fuzz-i386.base" \
"$DEST_DIR/qemu-fuzz-i386-target-$target"
fi
done
echo "Done. The fuzzers are located in $DEST_DIR"
exit 0