记一个AddressSanitizer（ASAN）linux下的内存分析神器的问题

感谢万能的互联网，我向google提出的issue很快就得到了工程师回复，解决了我的问题。

我的问题是这样的：

AddressSanitizer can't detect some global buffer overflow!　 #1285

 Closed

yangyongzhen opened this issue yesterday · 1 comment

yangyongzhen commented yesterday

what a pity! AddressSanitizer can't detect some global buffer overflow! Even if the mistake or code bugs is so obvious。 for example，this code bellow, guess what you will get, ...... U08 IP[10]; U08 IP1[10]; int main() {          memset(IP1,0x3A,10);     memcpy(IP,"123456789021111111111",17);     IP[15] = 12;     printf("IP1[0]:%d\n",IP1[0]);     printf("IP1[1]:%d\n",IP1[1]);     printf("IP1[2]:%d\n",IP1[2]);     printf("IP[10]:%d\n",IP[10]);     printf("IP[11]:%d\n",IP[11]);     printf("IP[15]:%d\n",IP[15]);     printf("IP1[0]:%d\n",IP1[0]);     printf("IP1[1]:%d\n",IP1[1]);     printf("IP1[2]:%d\n",IP1[2]); } 。。。。。。 扫描二维码关注公众号，回复： 11477296 查看本文章 use cflags= -std=gnu99 -Wall -fno-stack-protector -fno-omit-frame-pointer -fvar-tracking -g2 -fno-inline -fsanitize=address -fexceptions but AddressSanitizer can't detect this!!! if you add "static" before the global vars,like this: static U08 IP[10]; then AddressSanitizer can detect mistakes,, why?

melver commented 23 hours ago

Add -fno-common for C code. Globals that are placed in the common section (default for C) won't be separated by redzones, and therefore the OOB accesses in your example simply access IP1's memory.