c++ LLVM编译器-rt缺少libclang_rt.san-x86_64.a文件

xurqigkl  于 2023-03-25  发布在  其他
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我刚刚构建了LLVM/Clang compiler-rt并尝试了-fsanitize选项。但奇怪的是链接失败了,因为它找不到libclang_rt.san-x86_64.a

/usr/bin/ld: cannot find /home/hongxu/RESEARCH/llvm-git/obj/bin/../lib/clang/3.7.0/lib/linux/libclang_rt.san-x86_64.a: No such file or directory
clang-3.7: error: linker command failed with exit code 1 (use -v to see invocation)

当我切换到目录/home/hongxu/RESEARCH/llvm-git/obj/bin/../lib/clang/3.7.0/lib/linux/时,我发现还有其他库文件

# AddressSanitizer
libclang_rt.asan_cxx-x86_64.a
libclang_rt.asan-preinit-x86_64.a
libclang_rt.asan-x86_64.a
# DataFlowSanitizer
libclang_rt.dfsan-libc-x86_64.a
libclang_rt.dfsan-x86_64.a
# LeakSanitizer
libclang_rt.lsan-x86_64.a
# MemorySanitizer
libclang_rt.msan-x86_64.a
# ThreadSanitizer
libclang_rt.tsan-x86_64.a
# UndefinedBehaviorSanitizer
libclang_rt.ubsan_cxx-x86_64.a
libclang_rt.ubsan_standalone_cxx-x86_64.a
libclang_rt.ubsan_standalone-x86_64.a
libclang_rt.ubsan-x86_64.a

根据compiler-rt页面,我可以从名称中猜测它们的功能。
但是什么是libclang_rt.san-x86_64.a?我怎样才能得到它?

djp7away

djp7away1#

但奇怪的是,链接失败了,因为它找不到libclang_rt.san-x86_64.a。
是的,make install不安装一些需要的东西。其他时候,它会将它们安装在非标准位置。
它不安装的其他东西包括asan_symbolize.py,它用于从Address Sanitizer(ASan)中标记转储。
但是什么是libclang_rt.san-x86_64.a?我怎么才能得到它?
它是一个消毒库。你可能有它,你只是没有意识到它,因为它在一个非标准的位置。例如,在我的系统上(我自己构建LLVM/Clang):

$ find /usr -name libclang_rt.san-x86_64.a 2>/dev/null 
/usr/local/lib/clang/3.5.0/lib/linux/libclang_rt.san-x86_64.a

所以你需要做的是使用LD_LIBRARY_PATH(Linux)或DYLD_LIBRARY_PATH(OS X)来确保编译器驱动程序可以找到它。你应该***永远***不得不手动添加各种消毒库-编译器驱动程序应该总是为你添加它们。
为了完整起见,Clang 3.4在Linux上的/usr/local/lib/clang/3.4/lib/linux/上安装了消毒程序库;Clang 3.3在OS X上的/usr/local/lib/clang/3.3/lib/darwin/安装了它们。
你可以在源代码中改变搜索目录,它们会被编译器驱动程序自动拾取。我想我必须改变实际的源代码,因为我找不到一个配置选项来添加像/usr/local/lib/clang/<version>/lib/linux/这样的位置。看看tools/clang/lib/Frontend/InitHeaderSearch.cpp和朋友。这就是像.../include/c++/4.2.1这样的路径的来源。
顺便说一下,这里是如何使用Address Sanitizer和asan_symbolize.py的。首先,运行2to3asan_symbolize.py来修复Python人员在基本I/O方面的问题:

$ find Clang-3.5/ -name asan_symbolize.py
Clang-3.5/llvm/projects/compiler-rt/lib/asan/scripts/asan_symbolize.py
2to3 -w Clang-3.5/llvm/projects/compiler-rt/lib/asan/scripts/asan_symbolize.py

echo "" | Clang-3.5/llvm/projects/compiler-rt/lib/asan/scripts/asan_symbolize.py
# Fix errors 2to3 missed

然后,将其复制到一个众所周知的位置(或将其放在路径上):

sudo cp Clang-3.5/llvm/projects/compiler-rt/lib/asan/scripts/asan_symbolize.py /usr/local/bin

然后,对于您的项目:

export CPPFLAGS="-fsanitze=undefined -fsanitize=address"
export CFLAGS="-fsanitze=undefined -fsanitize=address"
export CXXFLAGS="-fsanitze=undefined -fsanitize=address -fno-sanitize=vptr"
export CC=/usr/local/bin/clang
export CXX=/usr/local/bin/clang++
export LD_LIBRARY_PATH=/usr/local/lib/clang/3.5.0/lib/linux

./configure
make
make check 2>&1 | asan_symbolize.py

CPPFLAGS实际上对于Autotools项目非常重要。否则,您会得到可怕的 *C编译器无法创建可执行文件 * 错误。
当您遇到ASan错误时,您将看到类似以下内容:

make test 2>&1 | asan_symbolize.py
...

/usr/local/bin/clang -fsanitize=address -Xlinker -export-dynamic
    -o python Modules/python.o libpython3.3m.a -ldl -lutil
    /usr/local/ssl/lib/libssl.a /usr/local/ssl/lib/libcrypto.a -lm
./python -E -S -m sysconfig --generate-posix-vars
=================================================================
==24064==ERROR: AddressSanitizer: heap-buffer-overflow on address
0x619000004020 at pc 0x4ed4b2 bp 0x7fff80fff010 sp 0x7fff80fff008
READ of size 4 at 0x619000004020 thread T0
  #0 0x4ed4b1 in PyObject_Free Python-3.3.5/./Objects/obmalloc.c:987
  #1 0x7a2141 in code_dealloc Python-3.3.5/./Objects/codeobject.c:359
  #2 0x620c00 in PyImport_ImportFrozenModuleObject
       Python-3.3.5/./Python/import.c:1098
  #3 0x620d5c in PyImport_ImportFrozenModule
       Python-3.3.5/./Python/import.c:1114
  #4 0x63fd07 in import_init Python-3.3.5/./Python/pythonrun.c:206
  #5 0x63f636 in _Py_InitializeEx_Private
       Python-3.3.5/./Python/pythonrun.c:369
  #6 0x681d77 in Py_Main Python-3.3.5/./Modules/main.c:648
  #7 0x4e6894 in main Python-3.3.5/././Modules/python.c:62
  #8 0x2abf9a525eac in __libc_start_main
       /home/aurel32/eglibc/eglibc-2.13/csu/libc-start.c:244
  #9 0x4e664c in _start (Python-3.3.5/./python+0x4e664c)

AddressSanitizer can not describe address in more detail (wild
memory access suspected).
SUMMARY: AddressSanitizer: heap-buffer-overflow
  Python-3.3.5/./Objects/obmalloc.c:987 PyObject_Free
Shadow bytes around the buggy address:
  0x0c327fff87b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c327fff87c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c327fff87d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c327fff87e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c327fff87f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c327fff8800: fa fa fa fa[fa]fa fa fa fa fa fa fa fa fa fa fa
  0x0c327fff8810: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c327fff8820: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c327fff8830: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c327fff8840: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c327fff8850: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07
  Heap left redzone:     fa
  Heap right redzone:    fb
  Freed heap region:     fd
  Stack left redzone:    f1
  Stack mid redzone:     f2
  Stack right redzone:   f3
  Stack partial redzone: f4
  Stack after return:    f5
  Stack use after scope: f8
  Global redzone:        f9
  Global init order:     f6
  Poisoned by user:      f7
  ASan internal:         fe
==24064==ABORTING
make: *** [pybuilddir.txt] Error 1

这里有一篇关于LLVM/Clang构建过程和在Python的Dynamic Analysis with Clang上使用santizers的更完整的文章。我写了一段时间,所以版本和配方都过时了。但是概念是一样的。

nimxete2

nimxete22#

感谢@jww的回答;但我的问题不一样
我收到了来自llvmdev邮件列表的回复(参见the thread),他们说:
libclang_rt.san现在已经消失了。新的编译器-rt版本不包含这个库,并且新的Clang没有使用它。
而且我编译失败了,因为我在编译之前没有同步其他llvm项目(我只把compiler-rt放在llvm/projects目录下,并从llvm build根目录进行编译)。
解决办法很简单:
尝试从头开始构建(删除构建目录,将所有llvm子项目同步到同一修订版,然后再次构建)。

vddsk6oq

vddsk6oq3#

clang 3.7中仍然使用这个库(当启用消毒程序时),但如果使用autotools编译,它将丢失。我通过寻找一个简单的解决方案找到了这个线程,但似乎没有任何解决方案,除了使用cmake构建所有自己。
另请参见LLVM Issue 22757 - libclang_rt.asan missing in clang-3.8 deb packages
另一个选项,我正在使用,是使用clang 3.6。

pdtvr36n

pdtvr36n4#

如果你从Linux发行版安装了clang,那么使用包管理器来搜索丢失的包。如果是Fedora和dnf,命令是dnf whatprovides

$ sudo dnf whatprovides '*/libclang_rt.asan-x86_64.so'
compiler-rt-15.0.7-1.fc37.x86_64 : LLVM "compiler-rt" runtime libraries
Repo        : updates
Matched from:
Filename    : /usr/lib64/clang/15.0.7/lib/libclang_rt.asan-x86_64.so
Filename    : /usr/lib64/clang/15.0.7/lib/linux/libclang_rt.asan-x86_64.so

swift-lang-5.7-1.fc37.x86_64 : The Swift programming language
Repo        : fedora
Matched from:
Filename    : /usr/libexec/swift/5.7/lib/clang/13.0.0/lib/linux/libclang_rt.asan-x86_64.so

因此,sudo dnf install -y compiler-rt将为您安装此文件。

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