asan 内存问题分析

1. 背景

在处理内存泄漏或者踩内存导致的coredump问题时候，常因堆栈信息不明确导致分析困难，本文旨在使用asan 处理内存相关问题；

常用的Sanitizer工具包括：

Address Sanitizer（ASan）：用于检测内存使用错误。
Leak Sanitizer（LSan）：用于检测内存泄漏。
Thread Sanitizer（TSan）：用于检测多线程间的数据竞争和死锁。
Memory Sanitizer（MSan）：用于检测使用未初始化内存的行为。

2. 编译构建版本

编译选项携带fsanitize 字段

a.构建ASan/LSan/MSan版本：

复制代码

CFLAGS+=-fsanitize=address
LDFLAGS+=-fsanitize=address

b.构建tsan版本：

复制代码

CFLAGS+=-fsanitize=thread
LDFLAGS+=-fsanitize=thread

3. 运行复现

直接运行

4. 示例

a. 代码如下:

cpp 复制代码

#include <string>
#include <vector>
#include <unordered_map>
#include <unordered_set>
#include <set>
#include <functional>
#include <algorithm>


int main() {

    int* aa = new int[5];
    aa[5] = 6;

    return 0;
}

b. 运行：

cpp 复制代码

=================================================================
==84697==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x603000000024 at pc 0x55fb86200acf bp 0x7ffc494247b0 sp 0x7ffc494247a0
WRITE of size 4 at 0x603000000024 thread T0
    #0 0x55fb86200ace in main /workspace/lhh/lhhcode/test/src/test.cpp:13
    #1 0x7f07d123bc86 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21c86)
    #2 0x55fb86200999 in _start (/workspace/lhh/lhhcode/test/build/test+0x999)

0x603000000024 is located 0 bytes to the right of 20-byte region [0x603000000010,0x603000000024)
allocated by thread T0 here:
    #0 0x7f07d16eb608 in operator new[](unsigned long) (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xe0608)
    #1 0x55fb86200a8b in main /workspace/lhh/lhhcode/test/src/test.cpp:12
    #2 0x7f07d123bc86 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21c86)

SUMMARY: AddressSanitizer: heap-buffer-overflow /workspace/lhh/lhhcode/test/src/test.cpp:13 in main
Shadow bytes around the buggy address:
  0x0c067fff7fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c067fff8000: fa fa 00 00[04]fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff8010: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff8020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff8050: 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
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==84697==ABORTING

从运行给出的信息分析：

main /workspace/lhh/lhhcode/test/src/test.cpp:13 出现了非法访问空内存
SUMMARY: AddressSanitizer: heap-buffer-overflow /workspace/lhh/lhhcode/test/src/test.cpp:13 in main 这里是内存申请的地方
aa $5$ = 6; 访问越界

参考文章：https://blog.csdn.net/qq_53619687/article/details/149354523?spm=1001.2101.3001.6650.3&utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7EBlogOpenSearchComplete%7ERate-3-149354523-blog-156462658.235%5Ev43%5Epc_blog_bottom_relevance_base8&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7EBlogOpenSearchComplete%7ERate-3-149354523-blog-156462658.235%5Ev43%5Epc_blog_bottom_relevance_base8&utm_relevant_index=4