use-of-uninitialized-value

[AlexanderLanin]

Description

doctest triggers clangs MemorySanititzer so it's not possible to see what my code would do.

Steps to reproduce

mkdir build && cd build && CXXFLAGS=-fsanitize=memory LDFLAGS=-fsanitize=memory cmake .. -DCMAKE_BUILD_TYPE=Debug && make && examples/all_features/all_features

With e.g. clang 10, not sure about other versions.

Extra information

• doctest version: tag: 2.4.0 = origin/master
• Operating System: Ubuntu 18 and 20
• Compiler+version: Clang 10 and trunk

Exact message

==10558==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x3c1f24 in std::_Rb_tree<std::pair<int, doctest::String>, std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)>, std::_Select1st<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> >, std::less<std::pair<int, doctest::String> >, std::allocator<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> > >::_M_get_insert_unique_pos(std::pair<int, doctest::String> const&) /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/stl_tree.h:2092:7
    #1 0x3c1968 in std::pair<std::_Rb_tree_iterator<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> >, bool> std::_Rb_tree<std::pair<int, doctest::String>, std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)>, std::_Select1st<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> >, std::less<std::pair<int, doctest::String> >, std::allocator<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> > >::_M_insert_unique<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> >(std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)>&&) /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/stl_tree.h:2148:4
    #2 0x379abd in std::map<std::pair<int, doctest::String>, doctest::IReporter* (*)(doctest::ContextOptions const&), std::less<std::pair<int, doctest::String> >, std::allocator<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> > >::insert(std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)>&&) /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/stl_map.h:809:21
    #3 0x330eb2 in doctest::detail::registerReporterImpl(char const*, int, doctest::IReporter* (*)(doctest::ContextOptions const&), bool) /home/alex/doctest/build/examples/all_features/../../../doctest/parts/doctest.cpp:3573:28
    #4 0x319f9e in int doctest::registerReporter<doctest::(anonymous namespace)::JUnitReporter>(char const*, int, bool) /home/alex/doctest/build/examples/all_features/../../../doctest/parts/doctest_fwd.h:1712:5
    #5 0x370f31 in __cxx_global_var_init.69 /home/alex/doctest/build/examples/all_features/../../../doctest/parts/doctest.cpp:2523:5
    #6 0x371af7 in _GLOBAL__sub_I_main.cpp /home/alex/doctest/build/examples/all_features/../../../examples/all_features/main.cpp
    #7 0x4738ac in __libc_csu_init (/home/alex/doctest/build/examples/all_features/all_features+0x4738ac)
    #8 0x7f94e1d0bb27 in __libc_start_main /build/glibc-2ORdQG/glibc-2.27/csu/../csu/libc-start.c:266
    #9 0x27a769 in _start (/home/alex/doctest/build/examples/all_features/all_features+0x27a769)

SUMMARY: MemorySanitizer: use-of-uninitialized-value /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/stl_tree.h:2092:7 in std::_Rb_tree<std::pair<int, doctest::String>, std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)>, std::_Select1st<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> >, std::less<std::pair<int, doctest::String> >, std::allocator<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> > >::_M_get_insert_unique_pos(std::pair<int, doctest::String> const&)
Exiting

Last non stl line is here:

namespace detail {
    void registerReporterImpl(const char* name, int priority, reporterCreatorFunc c, bool isReporter) {
        if(isReporter)
            getReporters().insert(reporterMap::value_type(reporterMap::key_type(priority, name), c)); //<< here!
        else
            getListeners().insert(reporterMap::value_type(reporterMap::key_type(priority, name), c));
    }
} // namespace detail

[onqtam]

I'm pretty sure the issue might be that you are using an uninstrumented libc++: https://github.com/google/sanitizers/wiki/MemorySanitizerLibcxxHowTo

This issue has been reported quite a bit in the past :)

[AlexanderLanin]

Oh... was not aware of that, sorry. Sounds like you are correct. Will report in ~2 hours...

[AlexanderLanin]

Ok sorry, this is probably a little off topic. But has someone done this already? I'm stuck.

After following the steps above to compile libc++ with MemoryWithOrigins, I'm running:
CC=clang CXX=clang++ cmake .. -DCMAKE_CXX_FLAGS="-fsanitize=memory -stdlib=libc++ -L/home/alex/llvm/build-msan/lib -lc++abi -I/home/alex/llvm/build-msan/include -pthread" -DCMAKE_BUILD_TYPE=Debug -GNinja && ninja && examples/all_features/all_feature

But I end up with:

==16494==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x388074 in std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::__put_character_sequence<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, char const*, unsigned long) /usr/local/bin/../include/c++/v1/ostream:727:13
    #1 0x366f66 in std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::operator<<<std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, char const*) /usr/local/bin/../include/c++/v1/ostream:869:12
    #2 0x35d2eb in doctest::(anonymous namespace)::ConsoleReporter::printVersion() /home/alex/doctest/build/../doctest/parts/doctest.cpp:2644:34
    #3 0x362c8c in doctest::(anonymous namespace)::ConsoleReporter::printIntro() /home/alex/doctest/build/../doctest/parts/doctest.cpp:2649:13
    #4 0x357891 in doctest::(anonymous namespace)::ConsoleReporter::test_run_start() /home/alex/doctest/build/../doctest/parts/doctest.cpp:2840:42
    #5 0x320239 in doctest::Context::run() /home/alex/doctest/build/../doctest/parts/doctest.cpp:3409:9
    #6 0x3288ac in main /home/alex/doctest/build/../examples/all_features/main.cpp:24:23
    #7 0x7f2d837c1b96 in __libc_start_main /build/glibc-2ORdQG/glibc-2.27/csu/../csu/libc-start.c:310
    #8 0x27c909 in _start (/home/alex/doctest/build/examples/all_features/all_features+0x27c909)

SUMMARY: MemorySanitizer: use-of-uninitialized-value /usr/local/bin/../include/c++/v1/ostream:727:13 in std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::__put_character_sequence<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, char const*, unsigned long)
Exiting

[onqtam]

I just followed the steps (without the gtest-related ones) and it worked on my machine - first time getting msan to work!
First I did this:

# clone LLVM
git clone --depth=1 https://github.com/llvm/llvm-project
cd llvm-project
mkdir build; cd build
# configure cmake
cmake -GNinja ../llvm \
	-DCMAKE_BUILD_TYPE=Release \
	-DLLVM_ENABLE_PROJECTS="libcxx;libcxxabi" \
	-DCMAKE_C_COMPILER=clang \
	-DCMAKE_CXX_COMPILER=clang++ \
	-DLLVM_USE_SANITIZER=MemoryWithOrigins
# build the libraries
cmake --build . -- cxx cxxabi

Then I entered this: (notice how I've substituted /path/to/libcxx_msan/ from their documentation with /home/onqtam/llvm-project/build/)

MSAN_CFLAGS="-fsanitize=memory -stdlib=libc++ -L/home/onqtam/llvm-project/build/lib -lc++abi -I/home/onqtam/llvm-project/build/include -I/home/onqtam/llvm-project/build/include/c++/v1"

And after that I compiled this program:

#define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
#include "doctest/doctest.h"
TEST_CASE("") {
    int a;
    CHECK(a == 1);
}

With this command (no need to pass the right include dirs to doctest because I include it properly in the .cpp file):

clang++ ${MSAN_CFLAGS} a.cpp -Wl,-rpath,/home/onqtam/llvm-project/build/lib

and running it gave me this:

onqtam@onqtam-ThinkPad-X1-Extreme:~/doctest$ ./a.out 
[doctest] doctest version is "2.4.0"
[doctest] run with "--help" for options
==10954==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x52f7f9 in doctest::detail::Result doctest::detail::Expression_lhs<int const&>::operator==<int>(int const&) (/home/onqtam/doctest/a.out+0x52f7f9)
    #1 0x4c69e7 in _DOCTEST_ANON_FUNC_8() (/home/onqtam/doctest/a.out+0x4c69e7)
    #2 0x4c1f6e in doctest::Context::run() (/home/onqtam/doctest/a.out+0x4c1f6e)
    #3 0x4c65b9 in main (/home/onqtam/doctest/a.out+0x4c65b9)
    #4 0x7fe41b5eb1e2 in __libc_start_main /build/glibc-5mDdLG/glibc-2.30/csu/../csu/libc-start.c:308:16
    #5 0x41fe6d in _start (/home/onqtam/doctest/a.out+0x41fe6d)

SUMMARY: MemorySanitizer: use-of-uninitialized-value (/home/onqtam/doctest/a.out+0x52f7f9) in doctest::detail::Result doctest::detail::Expression_lhs<int const&>::operator==<int>(int const&)
  ORIGIN: invalid (0). Might be a bug in MemorySanitizer origin tracking.
    This could still be a bug in your code, too!
Exiting

And when I initialized the variable a everything was fine. Hope this helps.

[AlexanderLanin]

Thanks, I went through your steps and noticed I missed a crucial detail. The part about -Wl,-rpath, since they didn't put it inside of MSAN_CFLAGS.

Now it works fine for me. Thanks!

Here is what I ended up with:
CC=clang CXX=clang++ cmake .. -DCMAKE_CXX_FLAGS="-fsanitize=memory -stdlib=libc++ -L/home/alex/llvm/build-msan/lib -lc++abi -I/home/alex/llvm/build-msan/include -pthread -Wl,-rpath,/home/alex/llvm/build-msan-debug/lib" -DCMAKE_BUILD_TYPE=Debug -GNinja && ninja && examples/all_features/all_features

[onqtam]

Glad it worked :)
I'll be closing this now. And maybe I should put it in the FAQ