c/c++动态检测内存错误利器 – ASan

原文链接:https://juejin.cn/post/6997201560140775461

ASan,即Address Sanitizer,是一个适用于c/c++的动态内存错误检测器,它由一个编译器检测模块(LLVM pass)和一个替换malloc函数的运行时库组成,在性能及检测内存错误方面都优于Valgrind。

一、适用平台

在LLVM3.1版之后,ASan就是其的一个组成部分,所以所有适用LLVM的平台,且llvm版本大于3.1的,都可以适用asan来检查c/c++内存错误。

对于gcc,则是4.8版本之后才加入asan,但是asan的完整功能则是要gcc版本在4.9.2以上。

二、强大功能

ASan作为编译器内置功能,支持检测各种内存错误:

  • 缓冲区溢出
    ①、堆内存溢出
    ②、栈上内存溢出
    ③、全局区缓存溢出
  • 悬空指针(引用)
    ①、使用释放后的堆上内存
    ②、使用返回的栈上内存
    ③、使用退出作用域的变量
  • 非法释放
    ①、重复释放
    ②、无效释放
  • 内存泄漏
  • 初始化顺序导致的问题

ASan和Valgrind对比如下图:

三、如何使用

1、使用ASan时,只需gcc选项加上-fsanitize=address;

2、如果想要在使用asan的时候获取更好的性能,可以加上O1或者更高的编译优化选项;

3、想要在错误信息中让栈追溯信息更友好,可以加上-fno-omit-frame-pointer选项。

本文针对linux x86-64平台,gcc编译器环境实验。

本文实验环境:

[root@yglocal ~]# lsb_release -a
LSB Version:    :core-4.1-amd64:core-4.1-noarch
Distributor ID: CentOS
Description:    CentOS Linux release 8.1.1911 (Core) 
Release:        8.1.1911
Codename:       Core
[root@yglocal ~]# uname -r
4.18.0-147.el8.x86_64
[root@yglocal ~]# gcc --version
gcc (GCC) 8.3.1 20190507 (Red Hat 8.3.1-4)
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE
复制代码

在centos上使用ASan,编译会报如下错误(gcc 4.8.5):

[root@localhost test]# gcc -g -O2 -fsanitize=address -fno-omit-frame-pointer hello.c 
/usr/bin/ld: cannot find /usr/lib64/libasan.so.0.0.0
collect2: error: ld returned 1 exit status
复制代码

安装libasan即可:

[root@localhost test]# yum install libasan
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注:ubuntu x86-64系统只需gcc版本高于4.8即可;但是在rhel/centos上使用ASan功能,除了gcc版本大于4.8之外,还需要安装libasan。

下面针对内存的几种c/c++常见内存错误,编写例子,看下ASan的报错输出:

1、堆缓冲区溢出

测试代码:

[root@yglocal asan_test]# vi heap_ovf_test.c 

#include <stdio.h>
#include <stdlib.h>
#include <string.h>


int main()
{
        char *heap_buf = (char*)malloc(32*sizeof(char));
        memcpy(heap_buf+30, "overflow", 8);    //在heap_buf的第30个字节开始,拷贝8个字符

        free(heap_buf);

        return 0;
}
复制代码

编译并运行:

[root@yglocal asan_test]# gcc -fsanitize=address -fno-omit-frame-pointer -o heap_ovf_test heap_ovf_test.c 
[root@yglocal asan_test]# ./heap_ovf_test 
=================================================================
==40602==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x603000000030 at pc 0x7f3de8f91a1d bp 0x7ffd4b4ebb60 sp 0x7ffd4b4eb308
WRITE of size 8 at 0x603000000030 thread T0
    #0 0x7f3de8f91a1c  (/lib64/libasan.so.5+0x40a1c)
    #1 0x400845 in main (/root/asan_test/heap_ovf_test+0x400845)
    #2 0x7f3de8bb1872 in __libc_start_main (/lib64/libc.so.6+0x23872)
    #3 0x40075d in _start (/root/asan_test/heap_ovf_test+0x40075d)

0x603000000030 is located 0 bytes to the right of 32-byte region [0x603000000010,0x603000000030)
allocated by thread T0 here:
    #0 0x7f3de9040ba8 in __interceptor_malloc (/lib64/libasan.so.5+0xefba8)
    #1 0x400827 in main (/root/asan_test/heap_ovf_test+0x400827)
    #2 0x7f3de8bb1872 in __libc_start_main (/lib64/libc.so.6+0x23872)

SUMMARY: AddressSanitizer: heap-buffer-overflow (/lib64/libasan.so.5+0x40a1c) 
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 00 00[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
==40602==ABORTING
[root@yglocal asan_test]# 
复制代码

可以看到asan报错:==40602==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x603000000030 at xxxx,下面也列出了发生heap-buffer-overflow时的调用链及heap buffer在哪里申请的。

2、栈缓冲区溢出

测试代码:

[root@yglocal asan_test]# vi stack_ovf_test.c 

#include <stdio.h>
#include <string.h>

int main()
{
        char stack_buf[4] = {0};
        strcpy(stack_buf, "1234");

        return 0;
}
复制代码

编译并运行:

[root@yglocal asan_test]# ./stack_ovf_test 
=================================================================
==38634==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffcf3d8b8d4 at pc 0x7f8714bbaa1d bp 0x7ffcf3d8b8a0 sp 0x7ffcf3d8b048
WRITE of size 5 at 0x7ffcf3d8b8d4 thread T0
    #0 0x7f8714bbaa1c  (/lib64/libasan.so.5+0x40a1c)
    #1 0x400949 in main (/root/asan_test/stack_ovf_test+0x400949)
    #2 0x7f87147da872 in __libc_start_main (/lib64/libc.so.6+0x23872)
    #3 0x4007cd in _start (/root/asan_test/stack_ovf_test+0x4007cd)

Address 0x7ffcf3d8b8d4 is located in stack of thread T0 at offset 36 in frame
    #0 0x400895 in main (/root/asan_test/stack_ovf_test+0x400895)

  This frame has 1 object(s):
    [32, 36) 'stack_buf' <== Memory access at offset 36 overflows this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow (/lib64/libasan.so.5+0x40a1c) 
Shadow bytes around the buggy address:
  0x10001e7a96c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10001e7a96d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10001e7a96e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10001e7a96f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10001e7a9700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x10001e7a9710: 00 00 00 00 00 00 f1 f1 f1 f1[04]f2 f2 f2 f3 f3
  0x10001e7a9720: f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10001e7a9730: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10001e7a9740: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10001e7a9750: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10001e7a9760: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
......
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可以看到asan报错:==38634==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffcf3d8b8d4 at xxx,发生stack buffer overflow时函数的调用链信息。

3、使用悬空指针

测试代码:

[root@yglocal asan_test]# vi dangling_pointer_test.c 

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
        char *p = (char*)malloc(32*sizeof(char));
        free(p);

        int a = p[1];

        return 0;
}
复制代码

编译运行:

[root@yglocal asan_test]# gcc -fsanitize=address -fno-omit-frame-pointer -o dangling_pointer_test dangling_pointer_test.c 
[root@yglocal asan_test]# ./dangling_pointer_test 
=================================================================
==83532==ERROR: AddressSanitizer: heap-use-after-free on address 0x603000000011 at pc 0x0000004007c4 bp 0x7ffd7f562760 sp 0x7ffd7f562750
READ of size 1 at 0x603000000011 thread T0
    #0 0x4007c3 in main (/root/asan_test/dangling_pointer_test+0x4007c3)
    #1 0x7f56196cd872 in __libc_start_main (/lib64/libc.so.6+0x23872)
    #2 0x4006ad in _start (/root/asan_test/dangling_pointer_test+0x4006ad)

0x603000000011 is located 1 bytes inside of 32-byte region [0x603000000010,0x603000000030)
freed by thread T0 here:
    #0 0x7f5619b5c7e0 in __interceptor_free (/lib64/libasan.so.5+0xef7e0)
    #1 0x400787 in main (/root/asan_test/dangling_pointer_test+0x400787)
    #2 0x7f56196cd872 in __libc_start_main (/lib64/libc.so.6+0x23872)

previously allocated by thread T0 here:
    #0 0x7f5619b5cba8 in __interceptor_malloc (/lib64/libasan.so.5+0xefba8)
    #1 0x400777 in main (/root/asan_test/dangling_pointer_test+0x400777)
    #2 0x7f56196cd872 in __libc_start_main (/lib64/libc.so.6+0x23872)

SUMMARY: AddressSanitizer: heap-use-after-free (/root/asan_test/dangling_pointer_test+0x4007c3) 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[fd]fd fd fd 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):
......
复制代码

4、使用栈上返回的变量

[root@yglocal asan_test]# vi use-after-return.c 

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int *ptr;
void get_pointer()
{
        int local[10];
        ptr = &local[0];
        return;
}


int main()
{
        get_pointer();

        printf("%d\n", *ptr);

        return 0;
}
复制代码

编译运行:

注:运行时,启用ASAN_OPTIONS=detect_stack_use_after_return=1标志,才能检测此种内存错误使用的情况。

[root@yglocal asan_test]# gcc -fsanitize=address -fno-omit-frame-pointer -o use_after_return use-after-return.c
[root@yglocal asan_test]# ASAN_OPTIONS=detect_stack_use_after_return=1 ./use_after_return 
=================================================================
==108419==ERROR: AddressSanitizer: stack-use-after-return on address 0x7fa2de200020 at pc 0x0000004009a2 bp 0x7ffccaef23c0 sp 0x7ffccaef23b0
READ of size 4 at 0x7fa2de200020 thread T0
    #0 0x4009a1 in main (/root/asan_test/use_after_return+0x4009a1)
    #1 0x7fa2e264d872 in __libc_start_main (/lib64/libc.so.6+0x23872)
    #2 0x4007cd in _start (/root/asan_test/use_after_return+0x4007cd)

Address 0x7fa2de200020 is located in stack of thread T0 at offset 32 in frame
    #0 0x400895 in get_pointer (/root/asan_test/use_after_return+0x400895)

  This frame has 1 object(s):
    [32, 72) 'local' <== Memory access at offset 32 is inside this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-use-after-return (/root/asan_test/use_after_return+0x4009a1) in main
Shadow bytes around the buggy address:
  0x0ff4dbc37fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ff4dbc37fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ff4dbc37fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ff4dbc37fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ff4dbc37ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0ff4dbc38000: f5 f5 f5 f5[f5]f5 f5 f5 f5 f5 f5 f5 f5 f5 f5 f5
  0x0ff4dbc38010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ff4dbc38020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ff4dbc38030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ff4dbc38040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ff4dbc38050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
......
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5、使用退出作用域的变量

测试代码:

[root@yglocal asan_test]# vi use-after-scope.c 

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
        int *p;
        {
                int num = 10;
                p = &num;
        }
        printf("%d/n", *p);

        return 0;
}
复制代码

编译并运行:

[root@yglocal asan_test]# ./use-after-scope 
=================================================================
==45490==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7fffda668b50 at pc 0x0000004009ea bp 0x7fffda668b10 sp 0x7fffda668b00
READ of size 4 at 0x7fffda668b50 thread T0
    #0 0x4009e9 in main (/root/asan_test/use-after-scope+0x4009e9)
    #1 0x7fc2194ca872 in __libc_start_main (/lib64/libc.so.6+0x23872)
    #2 0x40082d in _start (/root/asan_test/use-after-scope+0x40082d)

Address 0x7fffda668b50 is located in stack of thread T0 at offset 32 in frame
    #0 0x4008f5 in main (/root/asan_test/use-after-scope+0x4008f5)

  This frame has 1 object(s):
    [32, 36) 'num' <== Memory access at offset 32 is inside this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-use-after-scope (/root/asan_test/use-after-scope+0x4009e9) in main
Shadow bytes around the buggy address:
  0x10007b4c5110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007b4c5120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007b4c5130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007b4c5140: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007b4c5150: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x10007b4c5160: 00 00 00 00 00 00 f1 f1 f1 f1[f8]f2 f2 f2 f3 f3
  0x10007b4c5170: f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007b4c5180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007b4c5190: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007b4c51a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007b4c51b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
......
[root@yglocal asan_test]# 
复制代码

6、重复释放

​[root@yglocal asan_test]# vi invalid_free_test.c 


#include <stdio.h>
#include <stdlib.h>

int main()
{
        char *p = (char*)malloc(32*sizeof(char));
        free(p);
        free(p);

        return 0;
}

​
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运行并编译:

[root@yglocal asan_test]# gcc -fsanitize=address -fno-omit-frame-pointer -o invalid_free_test invalid_free_test.c 
[root@yglocal asan_test]# ./invalid_free_test 
=================================================================
==116778==ERROR: AddressSanitizer: attempting double-free on 0x603000000010 in thread T0:
    #0 0x7fab036ca7e0 in __interceptor_free (/lib64/libasan.so.5+0xef7e0)
    #1 0x400743 in main (/root/asan_test/invalid_free_test+0x400743)
    #2 0x7fab0323b872 in __libc_start_main (/lib64/libc.so.6+0x23872)
    #3 0x40065d in _start (/root/asan_test/invalid_free_test+0x40065d)

0x603000000010 is located 0 bytes inside of 32-byte region [0x603000000010,0x603000000030)
freed by thread T0 here:
    #0 0x7fab036ca7e0 in __interceptor_free (/lib64/libasan.so.5+0xef7e0)
    #1 0x400737 in main (/root/asan_test/invalid_free_test+0x400737)
    #2 0x7fab0323b872 in __libc_start_main (/lib64/libc.so.6+0x23872)

previously allocated by thread T0 here:
    #0 0x7fab036caba8 in __interceptor_malloc (/lib64/libasan.so.5+0xefba8)
    #1 0x400727 in main (/root/asan_test/invalid_free_test+0x400727)
    #2 0x7fab0323b872 in __libc_start_main (/lib64/libc.so.6+0x23872)

SUMMARY: AddressSanitizer: double-free (/lib64/libasan.so.5+0xef7e0) in __interceptor_free
==116778==ABORTING
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7、使用退出作用域的内存

测试代码:

[root@yglocal asan_test]# vi use-after-scope.c

#include <stdio.h>
#include <stdlib.h>

int main()
{
        int *p;
        {
                int num = 10;
                p = &num;
        }
        printf("%d/n", *p);

        return 0;
}
复制代码

编译并运行:

[root@yglocal asan_test]# gcc -fsanitize=address -fno-omit-frame-pointer -o use-after-scope use-after-scope.c 
[root@yglocal asan_test]# ./use-after-scope 
=================================================================
==118523==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7ffd35fafc60 at pc 0x0000004009ea bp 0x7ffd35fafc20 sp 0x7ffd35fafc10
READ of size 4 at 0x7ffd35fafc60 thread T0
    #0 0x4009e9 in main (/root/asan_test/use-after-scope+0x4009e9)
    #1 0x7f6d2c4ce872 in __libc_start_main (/lib64/libc.so.6+0x23872)
    #2 0x40082d in _start (/root/asan_test/use-after-scope+0x40082d)

Address 0x7ffd35fafc60 is located in stack of thread T0 at offset 32 in frame
    #0 0x4008f5 in main (/root/asan_test/use-after-scope+0x4008f5)

  This frame has 1 object(s):
    [32, 36) 'num' <== Memory access at offset 32 is inside this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-use-after-scope (/root/asan_test/use-after-scope+0x4009e9) in main
Shadow bytes around the buggy address:
  0x100026bedf30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100026bedf40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100026bedf50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100026bedf60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100026bedf70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x100026bedf80: 00 00 00 00 00 00 00 00 f1 f1 f1 f1[f8]f2 f2 f2
  0x100026bedf90: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
  0x100026bedfa0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100026bedfb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100026bedfc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100026bedfd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
......
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8、内存泄露检测

测试代码:

[root@yglocal asan_test]# vi memory_leak_test.c 


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char* get_systeminfo()
{
        char *p_system = (char*)malloc(38*sizeof(char));
        strcpy(p_system, "Linux version 4.18.0-147.el8.x86_64");
        return p_system;
}

int main()
{
        printf("system info:%s", get_systeminfo());
        return 0;
}
复制代码

编译并运行:

注:内存泄漏检测时,需带上ASAN_OPTIONS=detect_leaks=1参数启程序。

[root@yglocal asan_test]# gcc -fsanitize=address -fno-omit-frame-pointer -o memory_leak_test memory_leak_test.c
[root@yglocal asan_test]# ASAN_OPTIONS=detect_leaks=1  ./memory_leak_test 

=================================================================
==122316==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 38 byte(s) in 1 object(s) allocated from:
    #0 0x7fde593f3ba8 in __interceptor_malloc (/lib64/libasan.so.5+0xefba8)
    #1 0x400827 in get_systeminfo (/root/asan_test/memory_leak_test+0x400827)
    #2 0x400855 in main (/root/asan_test/memory_leak_test+0x400855)
    #3 0x7fde58f64872 in __libc_start_main (/lib64/libc.so.6+0x23872)

SUMMARY: AddressSanitizer: 38 byte(s) leaked in 1 allocation(s).
复制代码

四、输出优化

1、使用ASAN_OPTIONS参数启动程序

ASAN_OPTIONS=’stack_trace_format=”[frame=%n, function=%f, location=%S]”‘参数启动程序

[root@yglocal asan_test]# ASAN_OPTIONS='stack_trace_format="[frame=%n, function=%f, location=%S]"' ./heap_ovf_test 
=================================================================
==31061==ERROR: AddressSanitizer: heap-use-after-free on address 0x603000000010 at pc 0x7f181e836796 bp 0x7ffd87d62c30 sp 0x7ffd87d623a8
READ of size 2 at 0x603000000010 thread T0
[frame=0, function=<null>, location=<null>]
[frame=1, function=__interceptor_vprintf, location=<null>]
[frame=2, function=__interceptor_printf, location=<null>]
[frame=3, function=main, location=<null>]
[frame=4, function=__libc_start_main, location=<null>]
[frame=5, function=_start, location=<null>]

0x603000000010 is located 0 bytes inside of 32-byte region [0x603000000010,0x603000000030)
freed by thread T0 here:
[frame=0, function=__interceptor_free, location=<null>]
[frame=1, function=main, location=<null>]
[frame=2, function=__libc_start_main, location=<null>]

previously allocated by thread T0 here:
[frame=0, function=__interceptor_malloc, location=<null>]
[frame=1, function=main, location=<null>]
[frame=2, function=__libc_start_main, location=<null>]

SUMMARY: AddressSanitizer: heap-use-after-free (/lib64/libasan.so.5+0x55795) 
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[fd]fd fd fd 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
==31061==ABORTING
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2、使用asan_symbolize.py脚本

输出的调用链中信息更精确,可以对应到代码文件的具体某一行:

[root@yglocal asan_test]# gcc -fsanitize=address -fno-omit-frame-pointer -g -o heap_ovf_test heap_ovf_test.c 
[root@yglocal asan_test]# ./heap_ovf_test 2>&1 | ./asan_symbolize.py 
=================================================================
==66336==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x603000000030 at pc 0x7f0e8b19ea1d bp 0x7ffc0764d8a0 sp 0x7ffc0764d048
WRITE of size 8 at 0x603000000030 thread T0
    #0 0x7f0e8b19ea1c in __interceptor_strpbrk ??:?
    #1 0x400845 in main /root/asan_test/heap_ovf_test.c:9
    #1 0x7f0e8adbe872 in __libc_start_main ??:?
    #2 0x40075d in _start ??:?

0x603000000030 is located 0 bytes to the right of 32-byte region [0x603000000010,0x603000000030)
allocated by thread T0 here:
    #0 0x7f0e8b24dba8 in malloc ??:?
    #1 0x400827 in main /root/asan_test/heap_ovf_test.c:8
    #1 0x7f0e8adbe872 in __libc_start_main ??:?

SUMMARY: AddressSanitizer: heap-buffer-overflow (/lib64/libasan.so.5+0x40a1c)
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 00 00[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
==66336==ABORTING
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五、更多ASan配置参数

1、编译参数

2、运行时参数

查看看所有的运行时参数,可以用ASAN_OPTIONS=help=1启动程序,就会打印出所有支持的参数标志:

[root@yglocal asan_test]# ASAN_OPTIONS=help=1 ./use-after-scope 
Available flags for AddressSanitizer:
        quarantine_size
                - Deprecated, please use quarantine_size_mb.
        quarantine_size_mb
                - Size (in Mb) of quarantine used to detect use-after-free errors. Lower value may reduce memory usage but increase the chance of false negatives.
        thread_local_quarantine_size_kb
                - Size (in Kb) of thread local quarantine used to detect use-after-free errors. Lower value may reduce memory usage but increase the chance of false negatives. It is not advised to go lower than 64Kb, otherwise frequent transfers to global quarantine might affect performance.
        redzone
                - Minimal size (in bytes) of redzones around heap objects. Requirement: redzone >= 16, is a power of two.
        max_redzone
                - Maximal size (in bytes) of redzones around heap objects.
        debug
                - If set, prints some debugging information and does additional checks.
        report_globals
                - Controls the way to handle globals (0 - don't detect buffer overflow on globals, 1 - detect buffer overflow, 2 - print data about registered globals).
        check_initialization_order
                - If set, attempts to catch initialization order issues.
        replace_str
                - If set, uses custom wrappers and replacements for libc string functions to find more errors.
        replace_intrin
                - If set, uses custom wrappers for memset/memcpy/memmove intrinsics.
        detect_stack_use_after_return
                - Enables stack-use-after-return checking at run-time.
        min_uar_stack_size_log
                - Minimum fake stack size log.
        max_uar_stack_size_log
                - Maximum fake stack size log.
        uar_noreserve
                - Use mmap with 'noreserve' flag to allocate fake stack.
        max_malloc_fill_size
                - ASan allocator flag. max_malloc_fill_size is the maximal amount of bytes that will be filled with malloc_fill_byte on malloc.
        max_free_fill_size
                - ASan allocator flag. max_free_fill_size is the maximal amount of bytes that will be filled with free_fill_byte during free.
        malloc_fill_byte
                - Value used to fill the newly allocated memory.
        free_fill_byte
                - Value used to fill deallocated memory.
        allow_user_poisoning
                - If set, user may manually mark memory regions as poisoned or unpoisoned.
        sleep_before_dying
                - Number of seconds to sleep between printing an error report and terminating the program. Useful for debugging purposes (e.g. when one needs to attach gdb).
        sleep_after_init
                - Number of seconds to sleep after AddressSanitizer is initialized. Useful for debugging purposes (e.g. when one needs to attach gdb).
        check_malloc_usable_size
                - Allows the users to work around the bug in Nvidia drivers prior to 295.*.
        unmap_shadow_on_exit
                - If set, explicitly unmaps the (huge) shadow at exit.
        protect_shadow_gap
                - If set, mprotect the shadow gap
        print_stats
                - Print various statistics after printing an error message or if atexit=1.
        print_legend
                - Print the legend for the shadow bytes.
        print_scariness
                - Print the scariness score. Experimental.
        atexit
                - If set, prints ASan exit stats even after program terminates successfully.
        print_full_thread_history
                - If set, prints thread creation stacks for the threads involved in the report and their ancestors up to the main thread.
        poison_heap
                - Poison (or not) the heap memory on [de]allocation. Zero value is useful for benchmarking the allocator or instrumentator.
        poison_partial
                - If true, poison partially addressable 8-byte aligned words (default=true). This flag affects heap and global buffers, but not stack buffers.
        poison_array_cookie
                - Poison (or not) the array cookie after operator new[].
        alloc_dealloc_mismatch
                - Report errors on malloc/delete, new/free, new/delete[], etc.
        new_delete_type_mismatch
                - Report errors on mismatch between size of new and delete.
        strict_init_order
                - If true, assume that dynamic initializers can never access globals from other modules, even if the latter are already initialized.
        start_deactivated
                - If true, ASan tweaks a bunch of other flags (quarantine, redzone, heap poisoning) to reduce memory consumption as much as possible, and restores them to original values when the first instrumented module is loaded into the process. This is mainly intended to be used on Android. 
        detect_invalid_pointer_pairs
                - If >= 2, detect operations like <, <=, >, >= and - on invalid pointer pairs (e.g. when pointers belong to different objects); If == 1, detect invalid operations only when both pointers are non-null.
        detect_container_overflow
                - If true, honor the container overflow annotations. See https://github.com/google/sanitizers/wiki/AddressSanitizerContainerOverflow
        detect_odr_violation
                - If >=2, detect violation of One-Definition-Rule (ODR); If ==1, detect ODR-violation only if the two variables have different sizes
        suppressions
                - Suppressions file name.
        halt_on_error
                - Crash the program after printing the first error report (WARNING: USE AT YOUR OWN RISK!)
        use_odr_indicator
                - Use special ODR indicator symbol for ODR violation detection
        allocator_frees_and_returns_null_on_realloc_zero
                - realloc(p, 0) is equivalent to free(p) by default (Same as the POSIX standard). If set to false, realloc(p, 0) will return a pointer to an allocated space which can not be used.
        verify_asan_link_order
                - Check position of ASan runtime in library list (needs to be disabled when other library has to be preloaded system-wide)
        symbolize
                - If set, use the online symbolizer from common sanitizer runtime to turn virtual addresses to file/line locations.
        external_symbolizer_path
                - Path to external symbolizer. If empty, the tool will search $PATH for the symbolizer.
        allow_addr2line
                - If set, allows online symbolizer to run addr2line binary to symbolize stack traces (addr2line will only be used if llvm-symbolizer binary is unavailable.
        strip_path_prefix
                - Strips this prefix from file paths in error reports.
        fast_unwind_on_check
                - If available, use the fast frame-pointer-based unwinder on internal CHECK failures.
        fast_unwind_on_fatal
                - If available, use the fast frame-pointer-based unwinder on fatal errors.
        fast_unwind_on_malloc
                - If available, use the fast frame-pointer-based unwinder on malloc/free.
        handle_ioctl
                - Intercept and handle ioctl requests.
        malloc_context_size
                - Max number of stack frames kept for each allocation/deallocation.
        log_path
                - Write logs to "log_path.pid". The special values are "stdout" and "stderr". The default is "stderr".
        log_exe_name
                - Mention name of executable when reporting error and append executable name to logs (as in "log_path.exe_name.pid").
        log_to_syslog
                - Write all sanitizer output to syslog in addition to other means of logging.
        verbosity
                - Verbosity level (0 - silent, 1 - a bit of output, 2+ - more output).
        detect_leaks
                - Enable memory leak detection.
        leak_check_at_exit
                - Invoke leak checking in an atexit handler. Has no effect if detect_leaks=false, or if __lsan_do_leak_check() is called before the handler has a chance to run.
        allocator_may_return_null
                - If false, the allocator will crash instead of returning 0 on out-of-memory.
        print_summary
                - If false, disable printing error summaries in addition to error reports.
        print_module_map
                - OS X only (0 - don't print, 1 - print only once before process exits, 2 - print after each report).
        check_printf
                - Check printf arguments.
        handle_segv
                - Controls custom tool's SIGSEGV handler (0 - do not registers the handler, 1 - register the handler and allow user to set own, 2 - registers the handler and block user from changing it). 
        handle_sigbus
                - Controls custom tool's SIGBUS handler (0 - do not registers the handler, 1 - register the handler and allow user to set own, 2 - registers the handler and block user from changing it). 
        handle_abort
                - Controls custom tool's SIGABRT handler (0 - do not registers the handler, 1 - register the handler and allow user to set own, 2 - registers the handler and block user from changing it). 
        handle_sigill
                - Controls custom tool's SIGILL handler (0 - do not registers the handler, 1 - register the handler and allow user to set own, 2 - registers the handler and block user from changing it). 
        handle_sigfpe
                - Controls custom tool's SIGFPE handler (0 - do not registers the handler, 1 - register the handler and allow user to set own, 2 - registers the handler and block user from changing it). 
        allow_user_segv_handler
                - Deprecated. True has no effect, use handle_sigbus=1. If false, handle_*=1 will be upgraded to handle_*=2.
        use_sigaltstack
                - If set, uses alternate stack for signal handling.
        detect_deadlocks
                - If set, deadlock detection is enabled.
        clear_shadow_mmap_threshold
                - Large shadow regions are zero-filled using mmap(NORESERVE) instead of memset(). This is the threshold size in bytes.
        color
                - Colorize reports: (always|never|auto).
        legacy_pthread_cond
                - Enables support for dynamic libraries linked with libpthread 2.2.5.
        intercept_tls_get_addr
                - Intercept __tls_get_addr.
        help
                - Print the flag descriptions.
        mmap_limit_mb
                - Limit the amount of mmap-ed memory (excluding shadow) in Mb; not a user-facing flag, used mosly for testing the tools
        hard_rss_limit_mb
                - Hard RSS limit in Mb. If non-zero, a background thread is spawned at startup which periodically reads RSS and aborts the process if the limit is reached
        soft_rss_limit_mb
                - Soft RSS limit in Mb. If non-zero, a background thread is spawned at startup which periodically reads RSS. If the limit is reached all subsequent malloc/new calls will fail or return NULL (depending on the value of allocator_may_return_null) until the RSS goes below the soft limit. This limit does not affect memory allocations other than malloc/new.
        heap_profile
                - Experimental heap profiler, asan-only
        allocator_release_to_os_interval_ms
                - Experimental. Only affects a 64-bit allocator. If set, tries to release unused memory to the OS, but not more often than this interval (in milliseconds). Negative values mean do not attempt to release memory to the OS.

        can_use_proc_maps_statm
                - If false, do not attempt to read /proc/maps/statm. Mostly useful for testing sanitizers.
        coverage
                - If set, coverage information will be dumped at program shutdown (if the coverage instrumentation was enabled at compile time).
        coverage_dir
                - Target directory for coverage dumps. Defaults to the current directory.
        full_address_space
                - Sanitize complete address space; by default kernel area on 32-bit platforms will not be sanitized
        print_suppressions
                - Print matched suppressions at exit.
        disable_coredump
                - Disable core dumping. By default, disable_coredump=1 on 64-bit to avoid dumping a 16T+ core file. Ignored on OSes that don't dump core by default and for sanitizers that don't reserve lots of virtual memory.
        use_madv_dontdump
                - If set, instructs kernel to not store the (huge) shadow in core file.
        symbolize_inline_frames
                - Print inlined frames in stacktraces. Defaults to true.
        symbolize_vs_style
                - Print file locations in Visual Studio style (e.g:  file(10,42): ...
        dedup_token_length
                - If positive, after printing a stack trace also print a short string token based on this number of frames that will simplify deduplication of the reports. Example: 'DEDUP_TOKEN: foo-bar-main'. Default is 0.
        stack_trace_format
                - Format string used to render stack frames. See sanitizer_stacktrace_printer.h for the format description. Use DEFAULT to get default format.
        no_huge_pages_for_shadow
                - If true, the shadow is not allowed to use huge pages. 
        strict_string_checks
                - If set check that string arguments are properly null-terminated
        intercept_strstr
                - If set, uses custom wrappers for strstr and strcasestr functions to find more errors.
        intercept_strspn
                - If set, uses custom wrappers for strspn and strcspn function to find more errors.
        intercept_strtok
                - If set, uses a custom wrapper for the strtok function to find more errors.
        intercept_strpbrk
                - If set, uses custom wrappers for strpbrk function to find more errors.
        intercept_strlen
                - If set, uses custom wrappers for strlen and strnlen functions to find more errors.
        intercept_strndup
                - If set, uses custom wrappers for strndup functions to find more errors.
        intercept_strchr
                - If set, uses custom wrappers for strchr, strchrnul, and strrchr functions to find more errors.
        intercept_memcmp
                - If set, uses custom wrappers for memcmp function to find more errors.
        strict_memcmp
                - If true, assume that memcmp(p1, p2, n) always reads n bytes before comparing p1 and p2.
        intercept_memmem
                - If set, uses a wrapper for memmem() to find more errors.
        intercept_intrin
                - If set, uses custom wrappers for memset/memcpy/memmove intrinsics to find more errors.
        intercept_stat
                - If set, uses custom wrappers for *stat functions to find more errors.
        intercept_send
                - If set, uses custom wrappers for send* functions to find more errors.
        decorate_proc_maps
                - If set, decorate sanitizer mappings in /proc/self/maps with user-readable names
        exitcode
                - Override the program exit status if the tool found an error
        abort_on_error
                - If set, the tool calls abort() instead of _exit() after printing the error report.
        suppress_equal_pcs
                - Deduplicate multiple reports for single source location in halt_on_error=false mode (asan only).
        print_cmdline
                - Print command line on crash (asan only).
        html_cov_report
                - Generate html coverage report.
        sancov_path
                - Sancov tool location.
        dump_instruction_bytes
                - If true, dump 16 bytes starting at the instruction that caused SEGV
        dump_registers
                - If true, dump values of CPU registers when SEGV happens. Only available on OS X for now.
        include
                - read more options from the given file
        include_if_exists
                - read more options from the given file (if it exists)
=================================================================
==48570==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7fff1ccea5b0 at pc 0x0000004009ea bp 0x7fff1ccea570 sp 0x7fff1ccea560
READ of size 4 at 0x7fff1ccea5b0 thread T0
    #0 0x4009e9 in main (/root/asan_test/use-after-scope+0x4009e9)
    #1 0x7f89ddaf0872 in __libc_start_main (/lib64/libc.so.6+0x23872)
    #2 0x40082d in _start (/root/asan_test/use-after-scope+0x40082d)

Address 0x7fff1ccea5b0 is located in stack of thread T0 at offset 32 in frame
    #0 0x4008f5 in main (/root/asan_test/use-after-scope+0x4008f5)

  This frame has 1 object(s):
    [32, 36) 'num' <== Memory access at offset 32 is inside this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-use-after-scope (/root/asan_test/use-after-scope+0x4009e9) in main
Shadow bytes around the buggy address:
  0x100063995460: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100063995470: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100063995480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100063995490: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000639954a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x1000639954b0: 00 00 f1 f1 f1 f1[f8]f2 f2 f2 f3 f3 f3 f3 00 00
  0x1000639954c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000639954d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000639954e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000639954f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100063995500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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
==48570==ABORTING
复制代码

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参考链接:github.com/google/sani…

作者:yg_hunter
链接:https://juejin.cn/post/6997201560140775461
来源:稀土掘金
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