c - Valgrind macOs 和错误系统调用参数 msg->desc.port.name 指向未初始化的字节

标签 c macos valgrind cc

我尝试在非常简单的项目中运行 valgrind 3.13 和 3.14(在 macOs 10.12.6 上)，但我遇到了以前从未在我的 linux 中遇到过的奇怪错误。

  1. 非常简单的 C 程序 main.c:

    int main() {
    return (0);
}

  2. 使用cc编译:

    $> cc main.c

  3. 使用 valgrind 运行我的简单程序:

    $> valgrind ./a.out

  4. valgrind 的输出:

    ==12768== Memcheck, a memory error detector
==12768== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==12768== Using Valgrind-3.14.0.SVN and LibVEX; rerun with -h for copyright info
==12768== Command: ./a.out
==12768==
==12768== Syscall param msg->desc.port.name points to uninitialised byte(s)
==12768==    at 0x10049434A: mach_msg_trap (in /usr/lib/system/libsystem_kernel.dylib)
==12768==    by 0x100493796: mach_msg (in /usr/lib/system/libsystem_kernel.dylib)
==12768==    by 0x10048D485: task_set_special_port (in /usr/lib/system/libsystem_kernel.dylib)
==12768==    by 0x10062910E: _os_trace_create_debug_control_port (in /usr/lib/system/libsystem_trace.dylib)
==12768==    by 0x100629458: _libtrace_init (in /usr/lib/system/libsystem_trace.dylib)
==12768==    by 0x1001599DF: libSystem_initializer (in /usr/lib/libSystem.B.dylib)
==12768==    by 0x100017A1A: ImageLoaderMachO::doModInitFunctions(ImageLoader::LinkContext const&) (in /usr/lib/dyld)
==12768==    by 0x100017C1D: ImageLoaderMachO::doInitialization(ImageLoader::LinkContext const&) (in /usr/lib/dyld)
==12768==    by 0x1000134A9: ImageLoader::recursiveInitialization(ImageLoader::LinkContext const&, unsigned int, char const*, ImageLoader::InitializerTimingList&, ImageLoader::UninitedUpwards&) (in /usr/lib/dyld)
==12768==    by 0x100013440: ImageLoader::recursiveInitialization(ImageLoader::LinkContext const&, unsigned int, char const*, ImageLoader::InitializerTimingList&, ImageLoader::UninitedUpwards&) (in /usr/lib/dyld)
==12768==    by 0x100012523: ImageLoader::processInitializers(ImageLoader::LinkContext const&, unsigned int, ImageLoader::InitializerTimingList&, ImageLoader::UninitedUpwards&) (in /usr/lib/dyld)
==12768==    by 0x1000125B8: ImageLoader::runInitializers(ImageLoader::LinkContext const&, ImageLoader::InitializerTimingList&) (in /usr/lib/dyld)
==12768==  Address 0x10488ac6c is on thread 1's stack
==12768==  in frame #2, created by task_set_special_port (???:)
==12768==  Uninitialised value was created by a stack allocation
==12768==    at 0x1006290A6: _os_trace_create_debug_control_port (in /usr/lib/system/libsystem_trace.dylib)
==12768==
==12768==
==12768== HEAP SUMMARY:
==12768==     in use at exit: 18,144 bytes in 162 blocks
==12768==   total heap usage: 178 allocs, 16 frees, 24,288 bytes allocated
==12768==
==12768== LEAK SUMMARY:
==12768==    definitely lost: 3,456 bytes in 54 blocks
==12768==    indirectly lost: 0 bytes in 0 blocks
==12768==      possibly lost: 72 bytes in 3 blocks
==12768==    still reachable: 200 bytes in 6 blocks
==12768==         suppressed: 14,416 bytes in 99 blocks
==12768== Rerun with --leak-check=full to see details of leaked memory
==12768==
==12768== For counts of detected and suppressed errors, rerun with: -v
==12768== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 4 from 4)

    trace这部分我不明白:

    ==12768== Syscall param msg->desc.port.name points to uninitialised byte(s)
==12768==    at 0x10049434A: mach_msg_trap (in /usr/lib/system/libsystem_kernel.dylib)
==12768==    by 0x100493796: mach_msg (in /usr/lib/system/libsystem_kernel.dylib)
==12768==    by 0x10048D485: task_set_special_port (in /usr/lib/system/libsystem_kernel.dylib)
==12768==    by 0x10062910E: _os_trace_create_debug_control_port (in /usr/lib/system/libsystem_trace.dylib)
==12768==    by 0x100629458: _libtrace_init (in /usr/lib/system/libsystem_trace.dylib)
==12768==    by 0x1001599DF: libSystem_initializer (in /usr/lib/libSystem.B.dylib)
==12768==    by 0x100017A1A: ImageLoaderMachO::doModInitFunctions(ImageLoader::LinkContext const&) (in /usr/lib/dyld)
==12768==    by 0x100017C1D: ImageLoaderMachO::doInitialization(ImageLoader::LinkContext const&) (in /usr/lib/dyld)
==12768==    by 0x1000134A9: ImageLoader::recursiveInitialization(ImageLoader::LinkContext const&, unsigned int, char const*, ImageLoader::InitializerTimingList&, ImageLoader::UninitedUpwards&) (in /usr/lib/dyld)
==12768==    by 0x100013440: ImageLoader::recursiveInitialization(ImageLoader::LinkContext const&, unsigned int, char const*, ImageLoader::InitializerTimingList&, ImageLoader::UninitedUpwards&) (in /usr/lib/dyld)
==12768==    by 0x100012523: ImageLoader::processInitializers(ImageLoader::LinkContext const&, unsigned int, ImageLoader::InitializerTimingList&, ImageLoader::UninitedUpwards&) (in /usr/lib/dyld)
==12768==    by 0x1000125B8: ImageLoader::runInitializers(ImageLoader::LinkContext const&, ImageLoader::InitializerTimingList&) (in /usr/lib/dyld)
==12768==  Address 0x10488ac6c is on thread 1's stack
==12768==  in frame #2, created by task_set_special_port (???:)
==12768==  Uninitialised value was created by a stack allocation
==12768==    at 0x1006290A6: _os_trace_create_debug_control_port (in /usr/lib/system/libsystem_trace.dylib)

我不明白为什么我的简单 return(0); 的堆摘要如此之大(178 次分配、16 次释放、24,288 字节分配)；程序。

最佳答案

Valgrind 有一个抑制错误的系统。抑制规则在特殊文件中指定，例如 $PREFIX/lib/valgrind/default.supp。用户可以使用 --gen-suppressions=full 帮助创建自己的规则，这将为遇到的每个错误打印抑制规则。然后用户可以根据自己的需要对其进行自定义。

我这样做是为了解决有问题的错误，效果很好!无需安装不稳定版本。如果您遇到其他您想忽略的报告错误，这也是一个很好的工具。

我将此文件保存为 ~/.valgrind.supp。

# false positive for any executable (it seems)
# macOS 10.12.6
# valgrind 3.13.0
{
    libtrace initialization false positive
    Memcheck:Param
    msg->desc.port.name
    fun:mach_msg_trap
    fun:mach_msg
    fun:task_set_special_port
    fun:_os_trace_create_debug_control_port
    fun:_libtrace_init
}

# 开始注释，{} 表示规则。第一行是规则的名称。第二个说明要抑制的工具和错误类型。 Param 表示无效的系统调用参数，下一行给出了抑制错误的参数。以下以 fun: 开头的行表示此抑制规则仅适用于 mach_msg_trap 由 task_set_special_port 调用的 mach_msg 调用时等等。这样，我们仅在 Valgrind 将 libtrace 初始化错误误认为是错误的这种非常特殊的情况下抑制错误。

如果您在命令行上提供参数 --suppressions=$HOME/.valgrind.supp 或将其放入 $VALGRIND_OPTS 或~/.valgrindrc。

关于c - Valgrind macOs 和错误系统调用参数 msg->desc.port.name 指向未初始化的字节，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/45270093/

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