mptest: fix MemorySanitizer: use-of-uninitialized-value

Fix MemorySanitizer: use-of-uninitialized-value error in "disconnecting and
blocking" promise::get_future call reported:

- Sjors/bitcoin#90 (comment)
- https://cirrus-ci.com/task/4658925234028544and

and fixed:

- Sjors/bitcoin#90 (comment)

An issue exists to add an MSAN CI job to catch errors like this more quickly in
the future #188

Error looks like:

[ TEST ] test.cpp:251: Calling IPC method, disconnecting and blocking during the call
...
MemorySanitizer: use-of-uninitialized-value
    #0 0x7f83ecb19853 in std::__1::promise<void>::get_future() /msan/llvm-project/libcxx/src/future.cpp:154:16
    #1 0x55bf563af03c in mp::test::TestCase251::run()::$_0::operator()() const /ci_container_base/ci/scratch/build-x86_64-pc-linux-gnu/src/ipc/libmultiprocess/test/./ipc/libmultiprocess/test/mp/test/test.cpp:280:16
    #2 0x55bf563af03c in decltype(std::declval<mp::test::TestCase251::run()::$_0&>()()) std::__1::__invoke[abi:de200100]<mp::test::TestCase251::run()::$_0&>(mp::test::TestCase251::run()::$_0&) /msan/cxx_build/include/c++/v1/__type_traits/invoke.h:179:25
    #3 0x55bf563af03c in void std::__1::__invoke_void_return_wrapper<void, true>::__call[abi:de200100]<mp::test::TestCase251::run()::$_0&>(mp::test::TestCase251::run()::$_0&) /msan/cxx_build/include/c++/v1/__type_traits/invoke.h:251:5
    #4 0x55bf563af03c in void std::__1::__invoke_r[abi:de200100]<void, mp::test::TestCase251::run()::$_0&>(mp::test::TestCase251::run()::$_0&) /msan/cxx_build/include/c++/v1/__type_traits/invoke.h:273:10
    #5 0x55bf563af03c in std::__1::__function::__alloc_func<mp::test::TestCase251::run()::$_0, std::__1::allocator<mp::test::TestCase251::run()::$_0>, void ()>::operator()[abi:de200100]() /msan/cxx_build/include/c++/v1/__functional/function.h:167:12
    #6 0x55bf563af03c in std::__1::__function::__func<mp::test::TestCase251::run()::$_0, std::__1::allocator<mp::test::TestCase251::run()::$_0>, void ()>::operator()() /msan/cxx_build/include/c++/v1/__functional/function.h:319:10
    #7 0x55bf565f1b25 in std::__1::__function::__value_func<void ()>::operator()[abi:de200100]() const /msan/cxx_build/include/c++/v1/__functional/function.h:436:12
    #8 0x55bf565f1b25 in std::__1::function<void ()>::operator()() const /msan/cxx_build/include/c++/v1/__functional/function.h:995:10
    #9 0x55bf565f1b25 in mp::test::FooImplementation::callFnAsync() /ci_container_base/ci/scratch/build-x86_64-pc-linux-gnu/src/ipc/libmultiprocess/test/./ipc/libmultiprocess/test/mp/test/foo.h:83:40
    #10 0x55bf565f1b25 in decltype(auto) mp::ProxyMethodTraits<mp::test::messages::FooInterface::CallFnAsyncParams, void>::invoke<mp::ServerInvokeContext<mp::ProxyServer<mp::test::messages::FooInterface>, capnp::CallContext<mp::test::messages::FooInterface::CallFnAsyncParams, mp::test::messages::FooInterface::CallFnAsyncResults>>>(mp::ServerInvokeContext<mp::ProxyServer<mp::test::messages::FooInterface>, capnp::CallContext<mp::test::messages::FooInterface::CallFnAsyncParams, mp::test::messages::FooInterface::CallFnAsyncResults>>&) /ci_container_base/ci/scratch/build-x86_64-pc-linux-gnu/src/ipc/libmultiprocess/test/./ipc/libmultiprocess/include/mp/proxy.h:288:16
    #11 0x55bf565f1b25 in decltype(auto) mp::ServerCall::invoke<mp::ServerInvokeContext<mp::ProxyServer<mp::test::messages::FooInterface>, capnp::CallContext<mp::test::messages::FooInterface::CallFnAsyncParams, mp::test::messages::FooInterface::CallFnAsyncResults>>>(mp::ServerInvokeContext<mp::ProxyServer<mp::test::messages::FooInterface>, capnp::CallContext<mp::test::messages::FooInterface::CallFnAsyncParams, mp::test::messages::FooInterface::CallFnAsyncResults>>&, mp::TypeList<>) const /ci_container_base/ci/scratch/build-x86_64-pc-linux-gnu/src/ipc/libmultiprocess/test/./ipc/libmultiprocess/include/mp/proxy-types.h:448:16
    #12 0x55bf565f1b25 in std::__1::enable_if<std::is_same<decltype(mp::Accessor<mp::foo_fields::Context, 17>::get(fp1.call_context.getParams())), mp::Context::Reader>::value, kj::Promise<mp::ServerInvokeContext<mp::ProxyServer<mp::test::messages::FooInterface>, capnp::CallContext<mp::test::messages::FooInterface::CallFnAsyncParams, mp::test::messages::FooInterface::CallFnAsyncResults>>::CallContext>>::type mp::PassField<mp::Accessor<mp::foo_fields::Context, 17>, mp::ServerInvokeContext<mp::ProxyServer<mp::test::messages::FooInterface>, capnp::CallContext<mp::test::messages::FooInterface::CallFnAsyncParams, mp::test::messages::FooInterface::CallFnAsyncResults>>, mp::ServerCall, mp::TypeList<>>(mp::Priority<1>, mp::TypeList<>, mp::ServerInvokeContext<mp::ProxyServer<mp::test::messages::FooInterface>, capnp::CallContext<mp::test::messages::FooInterface::CallFnAsyncParams, mp::test::messages::FooInterface::CallFnAsyncResults>>&, mp::ServerCall const&, mp::TypeList<>&&)::'lambda'()::operator()() /ci_container_base/ci/scratch/build-x86_64-pc-linux-gnu/src/ipc/libmultiprocess/test/./ipc/libmultiprocess/include/mp/type-context.h:121:24
    #13 0x55bf565f12d1 in kj::Function<void ()>::Impl<std::__1::enable_if<std::is_same<decltype(mp::Accessor<mp::foo_fields::Context, 17>::get(fp1.call_context.getParams())), mp::Context::Reader>::value, kj::Promise<mp::ServerInvokeContext<mp::ProxyServer<mp::test::messages::FooInterface>, capnp::CallContext<mp::test::messages::FooInterface::CallFnAsyncParams, mp::test::messages::FooInterface::CallFnAsyncResults>>::CallContext>>::type mp::PassField<mp::Accessor<mp::foo_fields::Context, 17>, mp::ServerInvokeContext<mp::ProxyServer<mp::test::messages::FooInterface>, capnp::CallContext<mp::test::messages::FooInterface::CallFnAsyncParams, mp::test::messages::FooInterface::CallFnAsyncResults>>, mp::ServerCall, mp::TypeList<>>(mp::Priority<1>, mp::TypeList<>, mp::ServerInvokeContext<mp::ProxyServer<mp::test::messages::FooInterface>, capnp::CallContext<mp::test::messages::FooInterface::CallFnAsyncParams, mp::test::messages::FooInterface::CallFnAsyncResults>>&, mp::ServerCall const&, mp::TypeList<>&&)::'lambda'()>::operator()() /ci_container_base/depends/x86_64-pc-linux-gnu/include/kj/function.h:142:14
    #14 0x55bf5641125e in kj::Function<void ()>::operator()() /ci_container_base/depends/x86_64-pc-linux-gnu/include/kj/function.h:119:12
    #15 0x55bf5641125e in void mp::Unlock<std::__1::unique_lock<std::__1::mutex>, kj::Function<void ()>&>(std::__1::unique_lock<std::__1::mutex>&, kj::Function<void ()>&) /ci_container_base/ci/scratch/build-x86_64-pc-linux-gnu/src/ipc/libmultiprocess/test/./ipc/libmultiprocess/include/mp/util.h:198:5
    #16 0x55bf5667e45b in void mp::Waiter::wait<mp::ProxyServer<mp::ThreadMap>::makeThread(capnp::CallContext<mp::ThreadMap::MakeThreadParams, mp::ThreadMap::MakeThreadResults>)::$_0::operator()() const::'lambda'()>(std::__1::unique_lock<std::__1::mutex>&, mp::ProxyServer<mp::ThreadMap>::makeThread(capnp::CallContext<mp::ThreadMap::MakeThreadParams, mp::ThreadMap::MakeThreadResults>)::$_0::operator()() const::'lambda'())::'lambda'()::operator()() const /ci_container_base/ci/scratch/build-x86_64-pc-linux-gnu/src/ipc/libmultiprocess/./ipc/libmultiprocess/include/mp/proxy-io.h:294:17
    #17 0x55bf5667e45b in void std::__1::condition_variable::wait<void mp::Waiter::wait<mp::ProxyServer<mp::ThreadMap>::makeThread(capnp::CallContext<mp::ThreadMap::MakeThreadParams, mp::ThreadMap::MakeThreadResults>)::$_0::operator()() const::'lambda'()>(std::__1::unique_lock<std::__1::mutex>&, mp::ProxyServer<mp::ThreadMap>::makeThread(capnp::CallContext<mp::ThreadMap::MakeThreadParams, mp::ThreadMap::MakeThreadResults>)::$_0::operator()() const::'lambda'())::'lambda'()>(std::__1::unique_lock<std::__1::mutex>&, mp::ProxyServer<mp::ThreadMap>::makeThread(capnp::CallContext<mp::ThreadMap::MakeThreadParams, mp::ThreadMap::MakeThreadResults>)::$_0::operator()() const::'lambda'()) /msan/cxx_build/include/c++/v1/__condition_variable/condition_variable.h:146:11
    #18 0x55bf5667e45b in void mp::Waiter::wait<mp::ProxyServer<mp::ThreadMap>::makeThread(capnp::CallContext<mp::ThreadMap::MakeThreadParams, mp::ThreadMap::MakeThreadResults>)::$_0::operator()() const::'lambda'()>(std::__1::unique_lock<std::__1::mutex>&, mp::ProxyServer<mp::ThreadMap>::makeThread(capnp::CallContext<mp::ThreadMap::MakeThreadParams, mp::ThreadMap::MakeThreadResults>)::$_0::operator()() const::'lambda'()) /ci_container_base/ci/scratch/build-x86_64-pc-linux-gnu/src/ipc/libmultiprocess/./ipc/libmultiprocess/include/mp/proxy-io.h:285:14
    #19 0x55bf5667e45b in mp::ProxyServer<mp::ThreadMap>::makeThread(capnp::CallContext<mp::ThreadMap::MakeThreadParams, mp::ThreadMap::MakeThreadResults>)::$_0::operator()() const /ci_container_base/ci/scratch/build-x86_64-pc-linux-gnu/src/ipc/libmultiprocess/./ipc/libmultiprocess/src/mp/proxy.cpp:404:34
    #20 0x55bf5667e45b in decltype(std::declval<mp::ProxyServer<mp::ThreadMap>::makeThread(capnp::CallContext<mp::ThreadMap::MakeThreadParams, mp::ThreadMap::MakeThreadResults>)::$_0>()()) std::__1::__invoke[abi:de200100]<mp::ProxyServer<mp::ThreadMap>::makeThread(capnp::CallContext<mp::ThreadMap::MakeThreadParams, mp::ThreadMap::MakeThreadResults>)::$_0>(mp::ProxyServer<mp::ThreadMap>::makeThread(capnp::CallContext<mp::ThreadMap::MakeThreadParams, mp::ThreadMap::MakeThreadResults>)::$_0&&) /msan/cxx_build/include/c++/v1/__type_traits/invoke.h:179:25
    #21 0x55bf5667e45b in void std::__1::__thread_execute[abi:de200100]<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct>>, mp::ProxyServer<mp::ThreadMap>::makeThread(capnp::CallContext<mp::ThreadMap::MakeThreadParams, mp::ThreadMap::MakeThreadResults>)::$_0>(std::__1::tuple<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct>>, mp::ProxyServer<mp::ThreadMap>::makeThread(capnp::CallContext<mp::ThreadMap::MakeThreadParams, mp::ThreadMap::MakeThreadResults>)::$_0>&, std::__1::__tuple_indices<...>) /msan/cxx_build/include/c++/v1/__thread/thread.h:199:3
    #22 0x55bf5667e45b in void* std::__1::__thread_proxy[abi:de200100]<std::__1::tuple<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct>>, mp::ProxyServer<mp::ThreadMap>::makeThread(capnp::CallContext<mp::ThreadMap::MakeThreadParams, mp::ThreadMap::MakeThreadResults>)::$_0>>(void*) /msan/cxx_build/include/c++/v1/__thread/thread.h:208:3
    #23 0x7f83ec69caa3  (/lib/x86_64-linux-gnu/libc.so.6+0x9caa3) (BuildId: 42c84c92e6f98126b3e2230ebfdead22c235b667)
    #24 0x7f83ec729c3b  (/lib/x86_64-linux-gnu/libc.so.6+0x129c3b) (BuildId: 42c84c92e6f98126b3e2230ebfdead22c235b667)
[11:46:33.109]
  Member fields were destroyed
    #0 0x55bf56348abd in __sanitizer_dtor_callback_fields /msan/llvm-project/compiler-rt/lib/msan/msan_interceptors.cpp:1044:5
    #1 0x7f83ecb196de in ~promise /msan/cxx_build/include/c++/v1/future:1341:22
    #2 0x7f83ecb196de in std::__1::promise<void>::~promise() /msan/llvm-project/libcxx/src/future.cpp:151:1
    #3 0x55bf563adb36 in mp::test::TestCase251::run() /ci_container_base/ci/scratch/build-x86_64-pc-linux-gnu/src/ipc/libmultiprocess/test/./ipc/libmultiprocess/test/mp/test/test.cpp:293:1
    #4 0x55bf5669252e in kj::TestRunner::run()::'lambda'()::operator()() const /usr/src/kj/test.c++:318:11
    #5 0x55bf5669252e in kj::Maybe<kj::Exception> kj::runCatchingExceptions<kj::TestRunner::run()::'lambda'()>(kj::TestRunner::run()::'lambda'()&&) /usr/src/kj/exception.h:371:5
    #6 0x55bf5669071e in kj::TestRunner::run() /usr/src/kj/test.c++:318:11
    #7 0x55bf5668f977 in auto kj::TestRunner::getMain()::'lambda5'(auto&, auto&&...)::operator()<kj::TestRunner>(auto&, auto&&...) /usr/src/kj/test.c++:217:27
    #8 0x55bf5668f977 in auto kj::_::BoundMethod<kj::TestRunner&, kj::TestRunner::getMain()::'lambda5'(auto&, auto&&...), kj::TestRunner::getMain()::'lambda6'(auto&, auto&&...)>::operator()<>() /usr/src/kj/function.h:263:12
    #9 0x55bf5668f977 in kj::Function<kj::MainBuilder::Validity ()>::Impl<kj::_::BoundMethod<kj::TestRunner&, kj::TestRunner::getMain()::'lambda5'(auto&, auto&&...), kj::TestRunner::getMain()::'lambda6'(auto&, auto&&...)>>::operator()() /usr/src/kj/function.h:142:14
    #10 0x55bf56b7362c in kj::Function<kj::MainBuilder::Validity ()>::operator()() /usr/src/kj/function.h:119:12
    #11 0x55bf56b7362c in kj::MainBuilder::MainImpl::operator()(kj::StringPtr, kj::ArrayPtr<kj::StringPtr const>) /usr/src/kj/main.c++:623:5
    #12 0x55bf56b8865c in kj::Function<void (kj::StringPtr, kj::ArrayPtr<kj::StringPtr const>)>::Impl<kj::MainBuilder::MainImpl>::operator()(kj::StringPtr, kj::ArrayPtr<kj::StringPtr const>) /usr/src/kj/function.h:142:14
    #13 0x55bf56b6a592 in kj::Function<void (kj::StringPtr, kj::ArrayPtr<kj::StringPtr const>)>::operator()(kj::StringPtr, kj::ArrayPtr<kj::StringPtr const>) /usr/src/kj/function.h:119:12
    #14 0x55bf56b6a592 in kj::runMainAndExit(kj::ProcessContext&, kj::Function<void (kj::StringPtr, kj::ArrayPtr<kj::StringPtr const>)>&&, int, char**)::$_0::operator()() const /usr/src/kj/main.c++:228:5
    #15 0x55bf56b6a592 in kj::Maybe<kj::Exception> kj::runCatchingExceptions<kj::runMainAndExit(kj::ProcessContext&, kj::Function<void (kj::StringPtr, kj::ArrayPtr<kj::StringPtr const>)>&&, int, char**)::$_0>(kj::runMainAndExit(kj::ProcessContext&, kj::Function<void (kj::StringPtr, kj::ArrayPtr<kj::StringPtr const>)>&&, int, char**)::$_0&&) /usr/src/kj/exception.h:371:5
    #16 0x55bf56b69b5d in kj::runMainAndExit(kj::ProcessContext&, kj::Function<void (kj::StringPtr, kj::ArrayPtr<kj::StringPtr const>)>&&, int, char**) /usr/src/kj/main.c++:228:5
    #17 0x55bf5668be8f in main /usr/src/kj/test.c++:381:1
    #18 0x7f83ec62a1c9  (/lib/x86_64-linux-gnu/libc.so.6+0x2a1c9) (BuildId: 42c84c92e6f98126b3e2230ebfdead22c235b667)
    #19 0x7f83ec62a28a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2a28a) (BuildId: 42c84c92e6f98126b3e2230ebfdead22c235b667)
    #20 0x55bf5630b374 in _start (/ci_container_base/ci/scratch/build-x86_64-pc-linux-gnu/src/ipc/libmultiprocess/test/mptest+0x77374)
[11:46:33.109]
SUMMARY: MemorySanitizer: use-of-uninitialized-value /msan/llvm-project/libcxx/src/future.cpp:154:16 in std::__1::promise<void>::get_future()
Exiting

Author: ryanofsky

test/mp/test/test.cpp

@@ -268,12 +268,12 @@ KJ_TEST("Calling IPC method, disconnecting and blocking during the call")
     // ProxyServer objects associated with the connection. Having an in-progress
     // RPC call requires keeping the ProxyServer longer.
 
+    std::promise<void> signal;
     TestSetup setup{/*client_owns_connection=*/false};
     ProxyClient<messages::FooInterface>* foo = setup.client.get();
     KJ_EXPECT(foo->add(1, 2) == 3);
 
     foo->initThreadMap();
-    std::promise<void> signal;
     setup.server->m_impl->m_fn = [&] {
         EventLoopRef loop{*setup.server->m_context.loop};
         setup.client_disconnect();
@@ -289,6 +289,11 @@ KJ_TEST("Calling IPC method, disconnecting and blocking during the call")
     }
     KJ_EXPECT(disconnected);
 
+    // Now that the disconnect has been detected, set signal allowing the
+    // callFnAsync() IPC call to return. Since signalling may not wake up the
+    // thread right away, it is important for the signal variable to be declared
+    // *before* the TestSetup variable so is not destroyed while
+    // signal.get_future().get() is called.
     signal.set_value();
 }