[英]Why does the memory-sanitizer report use of an uninitialized value for std::map?
I'm using manjaro linux on x86-64.我在 x86-64 上使用 manjaro linux。 Memory-sanitizer in clang version 10.0.1 reported a use of uninitialized value error in std::map
, which quite surprised me. Memory-sanitizer in clang version 10.0.1 报告了 use of uninitialized value in std::map
错误,这让我很惊讶。 Did I do something wrong?我做错什么了吗?
$ cat test.cpp
#include <map>
int main() {
std::map<int, int> test;
test.insert({1,2});
}
$ clang++ -fsanitize=memory test.cpp && ./a.out
==51936==WARNING: MemorySanitizer: use-of-uninitialized-value
#0 0x562889eaad9a (/tmp/build/a.out+0x9fd9a)
#1 0x562889eaae28 (/tmp/build/a.out+0x9fe28)
#2 0x562889eaaba1 (/tmp/build/a.out+0x9fba1)
#3 0x562889eaa51e (/tmp/build/a.out+0x9f51e)
#4 0x562889eaa087 (/tmp/build/a.out+0x9f087)
#5 0x7f418e02b151 (/usr/lib/libc.so.6+0x28151)
#6 0x562889e2b1dd (/tmp/build/a.out+0x201dd)
SUMMARY: MemorySanitizer: use-of-uninitialized-value (/tmp/build/a.out+0x9fd9a)
Exiting
FWIW it looks like libc++ is more MSAN-friendly than stdlibc++ because compiling a similar FWIW 看起来 libc++ 比 stdlibc++ 对 MSAN 更友好,因为编译了类似的
#include <map>
#include <string>
int main(int argc, char** argv) {
std::map<int, std::string> m;
m[argc] = argv[argc - 1];
return 0;
}
code with the latter and running后者的代码并运行
% clang++ -fsanitize=memory -fno-omit-frame-pointer -g -O2 umr.cpp
results in a similar error, but doing导致类似的错误,但做
% clang++ -fsanitize=memory -fno-omit-frame-pointer -stdlib=libc++ -g -O2 umr.cpp && ./a.out
works fine (clang 13, Debian Sid).工作正常(clang 13,Debian Sid)。
When using MemorySanitizer, all libraries you use must be compiled with MemorySanitizer.使用 MemorySanitizer 时,您使用的所有库都必须使用 MemorySanitizer 进行编译。 Otherwise, there is a risk of false positives.否则,存在误报的风险。 This includes the C++ standard library itself.这包括 C++ 标准库本身。
You will find instructions for compiling libc++ with MemorySanitizer in the official sanitizers wiki:您可以在官方 sanitizers wiki 中找到使用 MemorySanitizer 编译 libc++ 的说明:
https://github.com/google/sanitizers/wiki/MemorySanitizerLibcxxHowTo https://github.com/google/sanitizers/wiki/MemorySanitizerLibcxxHowTo
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