Compile mysql with CFI enabled - mysql

Question

I want to compile mysql with CFI enabled by LLVM. The version of the softwares are as following:
clang-6.0
mysql-5.6.26
binutils-2.28.1
I can compile mysql successfully with the following configration:
CC="clang" CXX="clang++" CFLAGS="-g" cmake -DCMAKE_INSTALL_PREFIX=../mysql -DWITH_BOOST=./boost .
However, I can not compile mysql with the below configuration:
CC="clang" CXX="clang++" CFLAGS="-g -flto" CXXFLAGS="-g -flto" cmake -DCMAKE_INSTALL_PREFIX=../mysql -DWITH_BOOST=./boost .
The reported error is as following:
../mysys/libmysys.a: error adding symbols: Archive has no index; run ranlib to add one
clang-6.0: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [extra/comp_err] Error 1
The ../mysys/libmysys.a is constructed by the following command:
cd /home/zhangjun/work/mysql/mysql-5.6.26/mysys_ssl
&& /home/zhangjun/tools/cmake/cmake-3.9.1-Linux-x86_64/bin/cmake -P
CMakeFiles/mysys_ssl.dir/cmake_clean_target.cmake
cd /home/zhangjun/work/mysql/mysql-5.6.26/mysys_ssl && /home/zhangjun/tools/cmake/cmake-3.9.1-Linux-x86_64/bin/cmake -E cmake_link_script CMakeFiles/mysys_ssl.dir/link.txt --verbose=1
/usr/bin/ar qc libmysys_ssl.a CMakeFiles/mysys_ssl.dir/crypt_genhash_impl.cc.o CMakeFiles/mysys_ssl.dir/my_default.cc.o CMakeFiles/mysys_ssl.dir/my_getopt.cc.o CMakeFiles/mysys_ssl.dir/my_aes.cc.o CMakeFiles/mysys_ssl.dir/my_sha1.cc.o CMakeFiles/mysys_ssl.dir/my_sha2.cc.o CMakeFiles/mysys_ssl.dir/my_md5.cc.o CMakeFiles/mysys_ssl.dir/my_rnd.cc.o CMakeFiles/mysys_ssl.dir/my_murmur3.cc.o CMakeFiles/mysys_ssl.dir/my_aes_yassl.cc.o
/usr/bin/ranlib libmysys_ssl.a
How can I fix this error?
To fix this error, I sent a email to Caroline Tice, the author of "Enforcing Forward-Edge Control-Flow Integrity in GCC & LLVM"
He said I should use the ar and runlib of llvm. The above error is fixed by using the following configuration:
CC="clang" CXX="clang++" CFLAGS="-g -flto -fvisibility=hidden -fsanitize=cfi" CXXFLAGS="-g -flto -fvisibility=hidden -fsanitize=cfi" cmake -DCMAKE_{EXE,SHARED,MODULE}_LINKER_FLAGS="-flto -fsanitize=cfi" -DCMAKE_AR=/home/zhangjun/work/llvm/llvm-3.7.1/bin/llvm-ar -DCMAKE_RANLIB=/home/zhangjun/work/llvm/llvm-3.7.1/bin/llvm-ranlib -DCMAKE_NM=/home/zhangjun/work/llvm/llvm-3.7.1/bin/llvm-nm -DCMAKE_INSTALL_PREFIX=../mysql -DWITH_BOOST=./boost .
Unfortunately, there is anotehr error:
ld: /home/zhangjun/work/llvm/llvm/tools/gold/gold-plugin.cpp:879: ld_plugin_status allSymbolsReadHook(): Assertion `ObjFilename.second' failed.
clang-6.0: error: unable to execute command: Aborted (core dumped)
clang-6.0: error: linker command failed due to signal (use -v to see invocation)
make[2]: *** [extra/comp_err] Error 254
make[2]: Leaving directory `/home/zhangjun/work/mysql/mysql-5.6.26'
make[1]: *** [extra/CMakeFiles/comp_err.dir/all] Error 2
make[1]: Leaving directory `/home/zhangjun/work/mysql/mysql-5.6.26'
make: *** [all] Error 2
Can any body help me fix this error?

Answer 1

Try removing -flto from the flags. For some reason, with clang, I've had the link-time optimisation cause that problem.