Msan instrumented lrte

[dionescu]

Not an issue, but a feature request.

Given the recent changes that moved asan/msan/tsan to using LRTE, I think it would be really nice if the LRTE release would provide msan instrumented libc++ / libstdc++.

[mzhaom]

I might miss something, but isn't msan instrumented libstdc++ part of clang build coming with LRTE(or any prebuilt clang compiler)?

[dionescu]

Maybe https://github.com/google/sanitizers/wiki/MemorySanitizerLibcxxHowTo confused me. I tried their gtest example and it's failing but i think that may be a gtest msan bug.

[dionescu]

Upon further investigation, I still think LRTE is not using an MSAN instrumented libstdc++. For instance, one gets the MSAN error below when running bazel run --config=msan -- :bank-client. According to protocolbuffers/protobuf#1099, this error is not an MSAN bug in protobuf but is rather due to a non-instrumented libstdc++

INFO: Running command line: bazel-bin/examples/rpc/bank-client --alsologtostderr
==2977==WARNING: MemorySanitizer: use-of-uninitialized-value
#0 0x7fc7ed45f510 in google::protobuf::SimpleDescriptorDatabase::DescriptorIndex<std::pair<void const*, int> >::ValidateSymbolName(std::string const&) /home/dragos/.cache/bazel/_bazel_dragos/995c3226c255d07b9777857aa6c179dd/trunk-ro/external/protobuf/src/google/protobuf/descriptor_database.cc:238:24
#1 0x7fc7ed45d11f in google::protobuf::SimpleDescriptorDatabase::DescriptorIndex<std::pair<void const*, int> >::AddSymbol(std::string const&, std::pair<void const*, int>) /home/dragos/.cache/bazel/_bazel_dragos/995c3226c255d07b9777857aa6c179dd/trunk-ro/external/protobuf/src/google/protobuf/descriptor_database.cc:93:8
#2 0x7fc7ed451c22 in google::protobuf::SimpleDescriptorDatabase::DescriptorIndex<std::pair<void const*, int> >::AddFile(google::protobuf::FileDescriptorProto const&, std::pair<void const*, int>) /home/dragos/.cache/bazel/bazel_dragos/995c3226c255d07b9777857aa6c179dd/trunk-ro/external/protobuf/src/google/protobuf/descriptor_database.cc:68:10
#3 0x7fc7ed44e32b in google::protobuf::EncodedDescriptorDatabase::Add(void const, int) /home/dragos/.cache/bazel/bazel_dragos/995c3226c255d07b9777857aa6c179dd/trunk-ro/external/protobuf/src/google/protobuf/descriptor_database.cc:312:12
#4 0x7fc7ed353c0d in google::protobuf::DescriptorPool::InternalAddGeneratedFile(void const, int) /home/dragos/.cache/bazel/_bazel_dragos/995c3226c255d07b9777857aa6c179dd/trunk-ro/external/protobuf/src/google/protobuf/descriptor.cc:1157:3
#5 0x7fc7ed32dd52 in examples::protobuf_AddDesc_examples_2frpc_2fbank_2eproto() /home/dragos/.cache/bazel/_bazel_dragos/995c3226c255d07b9777857aa6c179dd/trunk-ro/bazel-out/crosstool_v2_clang-fastbuild/genfiles/examples/rpc/bank.pb.cc:105:3
#6 0x7fc7eda0a07c in __libc_csu_init /usr/lrte/v2/debug-src/src/glibc-2.21/csu/elf-init.c:88
#7 0x7fc7ebe2689e in __libc_start_main (/usr/lrte/v2/lib64/libc.so.6+0x2089e)
#8 0x7fc7ed2bd0c8 in _start /usr/lrte/v2/debug-src/src/glibc-2.21/csu/../sysdeps/x86_64/start.S:108

SUMMARY: MemorySanitizer: use-of-uninitialized-value /home/dragos/.cache/bazel/_bazel_dragos/995c3226c255d07b9777857aa6c179dd/trunk-ro/external/protobuf/src/google/protobuf/descriptor_database.cc:238:24 in google::protobuf::SimpleDescriptorDatabase::DescriptorIndex<std::pair<void const*, int> >::ValidateSymbolName(std::string const&)

[dionescu]

Or maybe LRTE has the instrumented version but the :msan config does not tell Bazel to use it.

[dionescu]

Noticed some more odd behaviour when building with LRTE. I would expect it to use libstdc++ from under /usr/lrte but ldd says differently. Am I missing something?

bazel build --crosstool_top //tools/lrte:toolchain :hello

ldd ../bazel-bin/examples/hello
../bazel-bin/examples/hello: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `CXXABI_1.3.8' not found (required by ../bazel-bin/examples/hello)
linux-vdso.so.1 => (0x00007ffdbca93000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f3e5f383000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f3e5f16d000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f3e5ef4f000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f3e5eb8a000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f3e5e884000)
/usr/lrte/v2/lib64/ld-linux-x86-64.so.2 => /lib64/ld-linux-x86-64.so.2 (0x00007f3e5f687000)

[dionescu]

Ah, I should have used the ldd from LRTE.

[dionescu]

I think this can be closed. The clang that comes with LRTE does not have a MSAN instrumented libstdc++ as far as I can tell. I have a script to create the instrumented version in my fork of LRTE: https://github.com/dionescu/lrte

[mzhaom]

Thanks for the update. Really appreciate your investigation and script.