Question

我试图使用valgrind，gperftools和libasan等工具在更复杂的系统中发现内存泄漏。我得到的泄漏是我无法摆脱的，所以我做了一个我能想到的最简单的程序。

为什么LeakSanitizer仍然报告泄密？

这是我的主文件：test.cc

// File: test.cc

int main()
{
    unsigned char* data = new unsigned char[1024];
    delete[] data;
    data = 0;

    return 0;
}

这是我的Makefile：

# Makefile

CC=g++
FLAGS=--std=c++11 -O0 -g -I. -fsanitize=address -fno-omit-frame-pointer -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-free
TGT=run
LINK=-static-libasan -ltcmalloc

all: $(TGT)

$(TGT): 
        $(CC) $(FLAGS) test.cc -o $(TGT) $(LINK)

clean:
        rm -f $(TGT)

您可以使用以下命令运行该程序：

env ASAN_OPTIONS=symbolize=1 ASAN_SYMBOLIZER_PATH=/usr/bin/llvm-symbolizer-3.8 ./run

分析是：

=================================================================
==23139==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 8 byte(s) in 1 object(s) allocated from:
    #0 0x481492 in operator new(unsigned long) (/home/user/tests/cpp/leakTest/basic/run+0x481492)
    #1 0x7f46c64bf0dd in InitModule src/malloc_extension.cc:212

SUMMARY: AddressSanitizer: 8 byte(s) leaked in 1 allocation(s).

我的系统：

user@computer:~$ lsb_release -a
LSB Version:    core-9.20160110ubuntu0.2-amd64:core-9.20160110ubuntu0.2-noarch:security-9.20160110ubuntu0.2-amd64:security-9.20160110ubuntu0.2-noarch
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.3 LTS
Release:    16.04
Codename:   xenial

user@computer:~/$ uname -a
Linux computer 4.4.0-103-generic #126-Ubuntu SMP Mon Dec 4 16:23:28 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

user@computer:~/$ dpkg -l | grep asan
ii  libasan2:amd64                                5.4.0-6ubuntu1~16.04.5                       amd64        AddressSanitizer -- a fast memory error detector

user@computer:~/$ dpkg -l | grep llvm
ii  libllvm3.6v5:amd64                            1:3.6.2-3ubuntu2                             amd64        Modular compiler and toolchain technologies, runtime library
ii  libllvm3.8:amd64                              1:3.8-2ubuntu4                               amd64        Modular compiler and toolchain technologies, runtime library
ii  libllvm4.0:amd64                              1:4.0-1ubuntu1~16.04.2                       amd64        Modular compiler and toolchain technologies, runtime library
ii  llvm                                          1:3.8-33ubuntu3.1                            amd64        Low-Level Virtual Machine (LLVM)
ii  llvm-3.8                                      1:3.8-2ubuntu4                               amd64        Modular compiler and toolchain technologies
ii  llvm-3.8-dev                                  1:3.8-2ubuntu4                               amd64        Modular compiler and toolchain technologies, libraries and headers
ii  llvm-3.8-runtime                              1:3.8-2ubuntu4                               amd64        Modular compiler and toolchain technologies, IR interpreter
ii  llvm-runtime                                  1:3.8-33ubuntu3.1                            amd64        Low-Level Virtual Machine (LLVM), bytecode interpreter

user@computer:~/$ dpkg -l | grep tcmalloc
ii  libtcmalloc-minimal4                          2.4-0ubuntu5.16.04.1                         amd64        efficient thread-caching malloc

user@computer:~/$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.4.0-6ubuntu1~16.04.5' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.5) 

user@computer:~/$ dpkg -l | grep libstdc
ii  libstdc++-5-dev:amd64                         5.4.0-6ubuntu1~16.04.5                       amd64        GNU Standard C++ Library v3 (development files)
ii  libstdc++6:amd64                              5.4.0-6ubuntu1~16.04.5                       amd64        GNU Standard C++ Library v3

编辑：嗯。如果我将Makefile中asan的链接从'-static-libasan'更改为'-lasan'，则不会报告泄漏。我不应该与-static-libasan联系吗？

Answer 1

我对tcmalloc不是很熟悉，但似乎故意泄漏了这个对象。指向泄漏：

Direct leak of 8 byte(s) in 1 object(s) allocated from:
    #0 0x481492 in operator new(unsigned long) (/home/user/tests/cpp/leakTest/basic/run+0x481492)
    #1 0x7f46c64bf0dd in InitModule src/malloc_extension.cc:212

与此源代码（github）相关联：

static void InitModule() {
  current_instance = new MallocExtension; // reported leak
#ifndef NO_HEAP_CHECK
  HeapLeakChecker::IgnoreObject(current_instance);
#endif
}

据报道，一些valgrind版本也检测到了这一点： https://github.com/gperftools/gperftools/issues/758

泄漏消毒剂检测泄漏

1 个答案: