Address Sanitizer
ASAN最早可以追溯到 LLVM 的 sanitizers项目（https://github.com/google/sanitizers），这个项目包含了AddressSanitizer，MemorySanitizer，ThreadSanitizer 和 LeakSanitizer等工具。这些工具可以检测用户空间的内存问题。通过在编译时加入指定的选项，就可以给用户程序加入 Address Sanitizer 功能。
其中Address Sanitizer（ASAN）工具是一个内存错误检测器，可以检测以下问题：
1）Out-of-bounds accesses to heap, stack and globals 堆、栈以及全局变量越界
2）Use-after-free 即访问dangling pointer，已经free的指针
3）Use-after-return (to some extent)
4）Double-free, invalid free
5）Memory leaks (experimental)
ASan基于shadow memory实现，目前已经集成到Clang 3.1和GCC 4.8以上版本。
编译选项
-fsanitize=address 使能Address Sanitizer工具
-fsanitize=leak 只使能Leak Sanitizer，检测内存泄漏问题
-fno-omit-frame-pointer 检测到内存错误时打印函数调用栈
-O1 代码优化选项，可以打印更清晰的函数调用栈
实例演示
1）栈溢出
#include <stdio.h>
#include <stdlib.h> int main(int argc, char **argv)
{
int stack[] = {}; stack[] = 0xdeadbeef; return ;
}
首先使用gcc stack-overflow.c -o stack-overflow编译，然后用./stack-overflow执行
linyao@chgao-virtual-machine:~/debugging/asan$ gcc stack-overflow.c -o stack-overflow
linyao@chgao-virtual-machine:~/debugging/asan$ ./stack-overflow
linyao@chgao-virtual-machine:~/debugging/asan$
程序没有任何报错，没有检测到栈越界。
接下来集成ASAN编译并执行，发现栈越界错误：
linyao@chgao-virtual-machine:~/debugging/asan$ gcc -fsanitize=address -fno-omit-frame-pointer stack-overflow.c -o stack-overflow
linyao@chgao-virtual-machine:~/debugging/asan$ ./stack-overflow
=================================================================
====ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffc6c0f67a0 at pc 0x0000004008fb bp 0x7ffc6c0f65d0 sp 0x7ffc6c0f65c0
WRITE of size at 0x7ffc6c0f67a0 thread T0
# 0x4008fa in main (/media/new/linyao/debugging/asan/stack-overflow+0x4008fa)
# 0x7fc449f7082f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.+0x2082f)
# 0x400748 in _start (/media/new/linyao/debugging/asan/stack-overflow+0x400748) Address 0x7ffc6c0f67a0 is located in stack of thread T0 at offset in frame
# 0x400825 in main (/media/new/linyao/debugging/asan/stack-overflow+0x400825) This frame has object(s):
[, ) 'stack' <== Memory access at offset 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 ??: main
Shadow bytes around the buggy address:
0x10000d816ca0:
0x10000d816cb0: f1 f1
0x10000d816cc0: f1 f1
0x10000d816cd0:
0x10000d816ce0:
=>0x10000d816cf0: [f4]f4 f3 f3 f3 f3
0x10000d816d00:
0x10000d816d10:
0x10000d816d20:
0x10000d816d30:
0x10000d816d40:
Shadow byte legend (one shadow byte represents application bytes):
Addressable:
Partially addressable:
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
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
====ABORTING
2）堆溢出
#include <stdio.h>
#include <stdlib.h> #define HEAP_SIZE (100) int main(int argc, char **argv)
{
int *heap = NULL; heap = (int *)malloc(HEAP_SIZE * sizeof(int));
if (NULL == heap)
return -; *(heap + HEAP_SIZE) = 0xdeadbeef; return ;
}
编译并执行：
linyao@chgao-virtual-machine:~/debugging/asan$ gcc -fsanitize=address -fno-omit-frame-pointer heap-overflow.c -o heap-overflow
linyao@chgao-virtual-machine:~/debugging/asan$ ./heap-overflow
=================================================================
====ERROR: AddressSanitizer: heap-buffer-overflow on address 0x61400000ffd0 at pc 0x0000004007ab bp 0x7fffa2f87bd0 sp 0x7fffa2f87bc0
WRITE of size at 0x61400000ffd0 thread T0
# 0x4007aa in main (/media/new/linyao/debugging/asan/heap-overflow+0x4007aa)
# 0x7fc8239b682f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.+0x2082f)
# 0x400668 in _start (/media/new/linyao/debugging/asan/heap-overflow+0x400668) 0x61400000ffd0 is located bytes to the right of -byte region [0x61400000fe40,0x61400000ffd0)
allocated by thread T0 here:
# 0x7fc823df8602 in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.+0x98602)
# 0x400756 in main (/media/new/linyao/debugging/asan/heap-overflow+0x400756)
# 0x7fc8239b682f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.+0x2082f) SUMMARY: AddressSanitizer: heap-buffer-overflow ??: main
Shadow bytes around the buggy address:
0x0c287fff9fa0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c287fff9fb0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c287fff9fc0: fa fa fa fa fa fa fa fa
0x0c287fff9fd0:
0x0c287fff9fe0:
=>0x0c287fff9ff0: [fa]fa fa fa fa fa
0x0c287fffa000: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c287fffa010: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c287fffa020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c287fffa030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c287fffa040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents application bytes):
Addressable:
Partially addressable:
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
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
====ABORTING
KASAN(Kernel Address Sanitizer)
Andrey Ryabinin 借鉴了 AddressSanitizer 的思想，并在 Linux 内核中实现了 Kernel Address Sanitizer。所以 Kasan 也可以看成是用于内核空间的 Address Sanitizer。
Kasan 是内核的一部分，使用时需要重新配置、编译并安装内核。Kasan 在 Linux 内核 4.0 版本时被引入内核，所以选择的内核代码需要高于 4.0 版本。另外，最基本的 Kasan 功能需要 GCC4.9.2 支持，更多的支持则需要 GCC5.0 及以上版本。
Linux内核内存检查工具还有kmemcheck。另外，也可以通过使能SLAB_DEBUG/SLUB_DEBUG/DEBUG_SLAB/DEBUG_PAGEALLOC等内核配置选项监控内存使用情况。