来自 boost::asio 的 Valgrind 错误

Question

我在分析我的程序时遇到了 valgrind 报告的奇怪错误。你能帮我找到他们的来源吗？

小例子

main.cpp:

#define BOOST_ASIO_ENABLE_HANDLER_TRACKING

#include "foo.h"
#include <iostream>

int main()
{
    boost::asio::io_service ioService;
    Foo foo(ioService);
    ioService.run();
    return EXIT_SUCCESS;
}

foo.h:

#include <boost/asio.hpp>

class Foo
{
private:
    boost::asio::ip::tcp::resolver resolver_;

public:
    Foo(boost::asio::io_service & ioService);

    virtual ~Foo()
    {}
};

foo.cpp:

#include "foo.h"

Foo::Foo(boost::asio::io_service & ioService) : resolver_(ioService)
{
}

当使用g++ -g3 -O0 -lboost_system -lpthread -o main ./main.cpp ./foo.cpp 编译并使用valgrind ./main 执行时，valgrind 报告5 errors 类型为无效写入。

==14905== Memcheck, a memory error detector
==14905== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==14905== Using Valgrind-3.15.0 and LibVEX; rerun with -h for copyright info
==14905== Command: ./main
==14905== 
==14905== Invalid write of size 1
==14905==    at 0x406724: boost::asio::detail::scheduler::scheduler(boost::asio::execution_context&, int) (scheduler.ipp:103)
==14905==    by 0x40CBF6: boost::asio::io_context::io_context(int) (io_context.ipp:44)
==14905==    by 0x40CE22: boost::asio::detail::resolver_service_base::resolver_service_base(boost::asio::io_context&) (resolver_service_base.ipp:40)
==14905==    by 0x40DC6A: boost::asio::detail::resolver_service<boost::asio::ip::tcp>::resolver_service(boost::asio::io_context&) (resolver_service.hpp:58)
==14905==    by 0x40DA56: boost::asio::execution_context::service* boost::asio::detail::service_registry::create<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, boost::asio::io_context>(void*) (service_registry.hpp:87)
==14905==    by 0x40C88F: boost::asio::detail::service_registry::do_use_service(boost::asio::execution_context::service::key const&, boost::asio::execution_context::service* (*)(void*), void*) (service_registry.ipp:132)
==14905==    by 0x40D86D: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::detail::service_registry::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (service_registry.hpp:39)
==14905==    by 0x40D6A0: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (io_context.hpp:39)
==14905==    by 0x40D596: boost::asio::basic_io_object<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, true>::basic_io_object(boost::asio::io_context&) (basic_io_object.hpp:224)
==14905==    by 0x40D498: boost::asio::ip::basic_resolver<boost::asio::ip::tcp>::basic_resolver(boost::asio::io_context&) (basic_resolver.hpp:101)
==14905==    by 0x40C544: Foo::Foo(boost::asio::io_context&) (foo.cpp:3)
==14905==    by 0x402D79: main (main.cpp:10)
==14905==  Address 0x5f06110 is 0 bytes after a block of size 240 alloc'd
==14905==    at 0x4C2E94F: operator new(unsigned long) (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==14905==    by 0x40CBE1: boost::asio::io_context::io_context(int) (io_context.ipp:44)
==14905==    by 0x40CE22: boost::asio::detail::resolver_service_base::resolver_service_base(boost::asio::io_context&) (resolver_service_base.ipp:40)
==14905==    by 0x40DC6A: boost::asio::detail::resolver_service<boost::asio::ip::tcp>::resolver_service(boost::asio::io_context&) (resolver_service.hpp:58)
==14905==    by 0x40DA56: boost::asio::execution_context::service* boost::asio::detail::service_registry::create<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, boost::asio::io_context>(void*) (service_registry.hpp:87)
==14905==    by 0x40C88F: boost::asio::detail::service_registry::do_use_service(boost::asio::execution_context::service::key const&, boost::asio::execution_context::service* (*)(void*), void*) (service_registry.ipp:132)
==14905==    by 0x40D86D: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::detail::service_registry::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (service_registry.hpp:39)
==14905==    by 0x40D6A0: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (io_context.hpp:39)
==14905==    by 0x40D596: boost::asio::basic_io_object<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, true>::basic_io_object(boost::asio::io_context&) (basic_io_object.hpp:224)
==14905==    by 0x40D498: boost::asio::ip::basic_resolver<boost::asio::ip::tcp>::basic_resolver(boost::asio::io_context&) (basic_resolver.hpp:101)
==14905==    by 0x40C544: Foo::Foo(boost::asio::io_context&) (foo.cpp:3)
==14905==    by 0x402D79: main (main.cpp:10)
==14905== 
==14905== Invalid write of size 1
==14905==    at 0x40672F: boost::asio::detail::scheduler::scheduler(boost::asio::execution_context&, int) (scheduler.ipp:103)
==14905==    by 0x40CBF6: boost::asio::io_context::io_context(int) (io_context.ipp:44)
==14905==    by 0x40CE22: boost::asio::detail::resolver_service_base::resolver_service_base(boost::asio::io_context&) (resolver_service_base.ipp:40)
==14905==    by 0x40DC6A: boost::asio::detail::resolver_service<boost::asio::ip::tcp>::resolver_service(boost::asio::io_context&) (resolver_service.hpp:58)
==14905==    by 0x40DA56: boost::asio::execution_context::service* boost::asio::detail::service_registry::create<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, boost::asio::io_context>(void*) (service_registry.hpp:87)
==14905==    by 0x40C88F: boost::asio::detail::service_registry::do_use_service(boost::asio::execution_context::service::key const&, boost::asio::execution_context::service* (*)(void*), void*) (service_registry.ipp:132)
==14905==    by 0x40D86D: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::detail::service_registry::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (service_registry.hpp:39)
==14905==    by 0x40D6A0: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (io_context.hpp:39)
==14905==    by 0x40D596: boost::asio::basic_io_object<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, true>::basic_io_object(boost::asio::io_context&) (basic_io_object.hpp:224)
==14905==    by 0x40D498: boost::asio::ip::basic_resolver<boost::asio::ip::tcp>::basic_resolver(boost::asio::io_context&) (basic_resolver.hpp:101)
==14905==    by 0x40C544: Foo::Foo(boost::asio::io_context&) (foo.cpp:3)
==14905==    by 0x402D79: main (main.cpp:10)
==14905==  Address 0x5f06111 is 1 bytes after a block of size 240 alloc'd
==14905==    at 0x4C2E94F: operator new(unsigned long) (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==14905==    by 0x40CBE1: boost::asio::io_context::io_context(int) (io_context.ipp:44)
==14905==    by 0x40CE22: boost::asio::detail::resolver_service_base::resolver_service_base(boost::asio::io_context&) (resolver_service_base.ipp:40)
==14905==    by 0x40DC6A: boost::asio::detail::resolver_service<boost::asio::ip::tcp>::resolver_service(boost::asio::io_context&) (resolver_service.hpp:58)
==14905==    by 0x40DA56: boost::asio::execution_context::service* boost::asio::detail::service_registry::create<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, boost::asio::io_context>(void*) (service_registry.hpp:87)
==14905==    by 0x40C88F: boost::asio::detail::service_registry::do_use_service(boost::asio::execution_context::service::key const&, boost::asio::execution_context::service* (*)(void*), void*) (service_registry.ipp:132)
==14905==    by 0x40D86D: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::detail::service_registry::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (service_registry.hpp:39)
==14905==    by 0x40D6A0: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (io_context.hpp:39)
==14905==    by 0x40D596: boost::asio::basic_io_object<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, true>::basic_io_object(boost::asio::io_context&) (basic_io_object.hpp:224)
==14905==    by 0x40D498: boost::asio::ip::basic_resolver<boost::asio::ip::tcp>::basic_resolver(boost::asio::io_context&) (basic_resolver.hpp:101)
==14905==    by 0x40C544: Foo::Foo(boost::asio::io_context&) (foo.cpp:3)
==14905==    by 0x402D79: main (main.cpp:10)
==14905== 
==14905== Invalid write of size 4
==14905==    at 0x40673D: boost::asio::detail::scheduler::scheduler(boost::asio::execution_context&, int) (scheduler.ipp:103)
==14905==    by 0x40CBF6: boost::asio::io_context::io_context(int) (io_context.ipp:44)
==14905==    by 0x40CE22: boost::asio::detail::resolver_service_base::resolver_service_base(boost::asio::io_context&) (resolver_service_base.ipp:40)
==14905==    by 0x40DC6A: boost::asio::detail::resolver_service<boost::asio::ip::tcp>::resolver_service(boost::asio::io_context&) (resolver_service.hpp:58)
==14905==    by 0x40DA56: boost::asio::execution_context::service* boost::asio::detail::service_registry::create<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, boost::asio::io_context>(void*) (service_registry.hpp:87)
==14905==    by 0x40C88F: boost::asio::detail::service_registry::do_use_service(boost::asio::execution_context::service::key const&, boost::asio::execution_context::service* (*)(void*), void*) (service_registry.ipp:132)
==14905==    by 0x40D86D: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::detail::service_registry::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (service_registry.hpp:39)
==14905==    by 0x40D6A0: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (io_context.hpp:39)
==14905==    by 0x40D596: boost::asio::basic_io_object<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, true>::basic_io_object(boost::asio::io_context&) (basic_io_object.hpp:224)
==14905==    by 0x40D498: boost::asio::ip::basic_resolver<boost::asio::ip::tcp>::basic_resolver(boost::asio::io_context&) (basic_resolver.hpp:101)
==14905==    by 0x40C544: Foo::Foo(boost::asio::io_context&) (foo.cpp:3)
==14905==    by 0x402D79: main (main.cpp:10)
==14905==  Address 0x5f06114 is 4 bytes after a block of size 240 alloc'd
==14905==    at 0x4C2E94F: operator new(unsigned long) (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==14905==    by 0x40CBE1: boost::asio::io_context::io_context(int) (io_context.ipp:44)
==14905==    by 0x40CE22: boost::asio::detail::resolver_service_base::resolver_service_base(boost::asio::io_context&) (resolver_service_base.ipp:40)
==14905==    by 0x40DC6A: boost::asio::detail::resolver_service<boost::asio::ip::tcp>::resolver_service(boost::asio::io_context&) (resolver_service.hpp:58)
==14905==    by 0x40DA56: boost::asio::execution_context::service* boost::asio::detail::service_registry::create<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, boost::asio::io_context>(void*) (service_registry.hpp:87)
==14905==    by 0x40C88F: boost::asio::detail::service_registry::do_use_service(boost::asio::execution_context::service::key const&, boost::asio::execution_context::service* (*)(void*), void*) (service_registry.ipp:132)
==14905==    by 0x40D86D: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::detail::service_registry::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (service_registry.hpp:39)
==14905==    by 0x40D6A0: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (io_context.hpp:39)
==14905==    by 0x40D596: boost::asio::basic_io_object<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, true>::basic_io_object(boost::asio::io_context&) (basic_io_object.hpp:224)
==14905==    by 0x40D498: boost::asio::ip::basic_resolver<boost::asio::ip::tcp>::basic_resolver(boost::asio::io_context&) (basic_resolver.hpp:101)
==14905==    by 0x40C544: Foo::Foo(boost::asio::io_context&) (foo.cpp:3)
==14905==    by 0x402D79: main (main.cpp:10)
==14905== 
@asio|1589278153.511608|0|resolver@0x1ffefff910.cancel
==14905== Invalid write of size 1
==14905==    at 0x406D20: boost::asio::detail::scheduler::stop_all_threads(boost::asio::detail::conditionally_enabled_mutex::scoped_lock&) (scheduler.ipp:543)
==14905==    by 0x406A9E: boost::asio::detail::scheduler::stop() (scheduler.ipp:257)
==14905==    by 0x40CC67: boost::asio::io_context::stop() (io_context.ipp:121)
==14905==    by 0x40CF79: boost::asio::detail::resolver_service_base::base_shutdown() (resolver_service_base.ipp:58)
==14905==    by 0x40DFD9: boost::asio::detail::resolver_service<boost::asio::ip::tcp>::shutdown() (resolver_service.hpp:65)
==14905==    by 0x405335: boost::asio::detail::service_registry::shutdown_services() (service_registry.ipp:44)
==14905==    by 0x40568C: boost::asio::execution_context::shutdown() (execution_context.ipp:41)
==14905==    by 0x405630: boost::asio::execution_context::~execution_context() (execution_context.ipp:34)
==14905==    by 0x4070A1: boost::asio::io_context::~io_context() (io_context.ipp:55)
==14905==    by 0x402DA2: main (main.cpp:9)
==14905==  Address 0x5f06110 is 0 bytes after a block of size 240 alloc'd
==14905==    at 0x4C2E94F: operator new(unsigned long) (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==14905==    by 0x40CBE1: boost::asio::io_context::io_context(int) (io_context.ipp:44)
==14905==    by 0x40CE22: boost::asio::detail::resolver_service_base::resolver_service_base(boost::asio::io_context&) (resolver_service_base.ipp:40)
==14905==    by 0x40DC6A: boost::asio::detail::resolver_service<boost::asio::ip::tcp>::resolver_service(boost::asio::io_context&) (resolver_service.hpp:58)
==14905==    by 0x40DA56: boost::asio::execution_context::service* boost::asio::detail::service_registry::create<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, boost::asio::io_context>(void*) (service_registry.hpp:87)
==14905==    by 0x40C88F: boost::asio::detail::service_registry::do_use_service(boost::asio::execution_context::service::key const&, boost::asio::execution_context::service* (*)(void*), void*) (service_registry.ipp:132)
==14905==    by 0x40D86D: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::detail::service_registry::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (service_registry.hpp:39)
==14905==    by 0x40D6A0: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (io_context.hpp:39)
==14905==    by 0x40D596: boost::asio::basic_io_object<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, true>::basic_io_object(boost::asio::io_context&) (basic_io_object.hpp:224)
==14905==    by 0x40D498: boost::asio::ip::basic_resolver<boost::asio::ip::tcp>::basic_resolver(boost::asio::io_context&) (basic_resolver.hpp:101)
==14905==    by 0x40C544: Foo::Foo(boost::asio::io_context&) (foo.cpp:3)
==14905==    by 0x402D79: main (main.cpp:10)
==14905== 
==14905== Invalid write of size 1
==14905==    at 0x4067E2: boost::asio::detail::scheduler::shutdown() (scheduler.ipp:111)
==14905==    by 0x405335: boost::asio::detail::service_registry::shutdown_services() (service_registry.ipp:44)
==14905==    by 0x40568C: boost::asio::execution_context::shutdown() (execution_context.ipp:41)
==14905==    by 0x405630: boost::asio::execution_context::~execution_context() (execution_context.ipp:34)
==14905==    by 0x4070A1: boost::asio::io_context::~io_context() (io_context.ipp:55)
==14905==    by 0x40D37A: boost::asio::detail::scoped_ptr<boost::asio::io_context>::reset(boost::asio::io_context*) (scoped_ptr.hpp:63)
==14905==    by 0x40CFD5: boost::asio::detail::resolver_service_base::base_shutdown() (resolver_service_base.ipp:64)
==14905==    by 0x40DFD9: boost::asio::detail::resolver_service<boost::asio::ip::tcp>::shutdown() (resolver_service.hpp:65)
==14905==    by 0x405335: boost::asio::detail::service_registry::shutdown_services() (service_registry.ipp:44)
==14905==    by 0x40568C: boost::asio::execution_context::shutdown() (execution_context.ipp:41)
==14905==    by 0x405630: boost::asio::execution_context::~execution_context() (execution_context.ipp:34)
==14905==    by 0x4070A1: boost::asio::io_context::~io_context() (io_context.ipp:55)
==14905==  Address 0x5f06111 is 1 bytes after a block of size 240 alloc'd
==14905==    at 0x4C2E94F: operator new(unsigned long) (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==14905==    by 0x40CBE1: boost::asio::io_context::io_context(int) (io_context.ipp:44)
==14905==    by 0x40CE22: boost::asio::detail::resolver_service_base::resolver_service_base(boost::asio::io_context&) (resolver_service_base.ipp:40)
==14905==    by 0x40DC6A: boost::asio::detail::resolver_service<boost::asio::ip::tcp>::resolver_service(boost::asio::io_context&) (resolver_service.hpp:58)
==14905==    by 0x40DA56: boost::asio::execution_context::service* boost::asio::detail::service_registry::create<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, boost::asio::io_context>(void*) (service_registry.hpp:87)
==14905==    by 0x40C88F: boost::asio::detail::service_registry::do_use_service(boost::asio::execution_context::service::key const&, boost::asio::execution_context::service* (*)(void*), void*) (service_registry.ipp:132)
==14905==    by 0x40D86D: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::detail::service_registry::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (service_registry.hpp:39)
==14905==    by 0x40D6A0: boost::asio::detail::resolver_service<boost::asio::ip::tcp>& boost::asio::use_service<boost::asio::detail::resolver_service<boost::asio::ip::tcp> >(boost::asio::io_context&) (io_context.hpp:39)
==14905==    by 0x40D596: boost::asio::basic_io_object<boost::asio::detail::resolver_service<boost::asio::ip::tcp>, true>::basic_io_object(boost::asio::io_context&) (basic_io_object.hpp:224)
==14905==    by 0x40D498: boost::asio::ip::basic_resolver<boost::asio::ip::tcp>::basic_resolver(boost::asio::io_context&) (basic_resolver.hpp:101)
==14905==    by 0x40C544: Foo::Foo(boost::asio::io_context&) (foo.cpp:3)
==14905==    by 0x402D79: main (main.cpp:10)
==14905== 
==14905== 
==14905== HEAP SUMMARY:
==14905==     in use at exit: 1 bytes in 1 blocks
==14905==   total heap usage: 18 allocs, 17 frees, 79,744 bytes allocated
==14905== 
==14905== LEAK SUMMARY:
==14905==    definitely lost: 0 bytes in 0 blocks
==14905==    indirectly lost: 0 bytes in 0 blocks
==14905==      possibly lost: 0 bytes in 0 blocks
==14905==    still reachable: 1 bytes in 1 blocks
==14905==         suppressed: 0 bytes in 0 blocks
==14905== Rerun with --leak-check=full to see details of leaked memory
==14905== 
==14905== For lists of detected and suppressed errors, rerun with: -s
==14905== ERROR SUMMARY: 5 errors from 5 contexts (suppressed: 0 from 0)

我在 openSUSE Leap 15.1、valgrind 3.15.0 和 boost 1.66.0 上使用 g++ 8.2.1（也使用 1.71.0 进行了测试）。

一些观察

• 没有宏BOOST_ASIO_ENABLE_HANDLER_TRACKING不会报错。
• 如果构造函数 Foo() 的主体在 foo.h 中（即整个代码在一个编译单元中），则不会报告错误。
• Foo 类中没有resolver_ 不会报告错误。

大图
我注意到我的一个更复杂的程序有时会忽略信号（也由 boost::asio 处理）。所以我添加了BOOST_ASIO_ENABLE_HANDLER_TRACKING，它开始崩溃（反复），valgrind 开始报告“无效写入”错误（随后出现“跳转到无效地址”类型的错误）。

推测

• 宏 BOOST_ASIO_ENABLE_HANDLER_TRACKING 在 boost::asio 中发现了一个错误，导致我的信号在没有宏的情况下被忽略。
• Valgrind 生成错误警报。
• 最有可能：我的代码包含一个不可原谅且明显的错误，我还看不到。

Answer 1

我没有看到不可原谅的错误。

我确实看到了可能的 ODR 违规行为。定义BOOST_ASIO_ENABLE_HANDLER_TRACKING 全局 或根本不定义。就目前而言，您有一个定义它的 TU，一个（或多个）没有定义它。这是UB。

我之前在我自己的代码库中看到过由于这种特殊情况而导致的 UB，所以我很确定这是你的问题。