#44. 用mudflap检测缓冲区溢出

用mudflap检测“stack/bbs上的变量访问错误”

1. 安装mudflap
#yum install libmudflap libmudflap-devel

2. 示例代码
test_44.c

static char onbss[128];

int main( int argc , char **argv )
{
    char onstack[128] = {0};
    int dummy;

    dummy = onbss[128];        // off-by-one bug
    dummy = onstack[128];    //ditto

    return 0;
}

3. 编译
gcc -g -fmudflap -o testflap test_44.c -lmudflap

4. 输出
[root@localhost helloworld]# ./testflap
*******
mudflap violation 1 (check/read): time=1317740344.659364 ptr=0x80c9c40 size=129
pc=0x1dca8d location=`test_44.c:8:2 (main)'
      /usr/lib/libmudflap.so.0(__mf_check+0x3d) [0x1dca8d]
      ./testflap(main+0x113) [0x8048807]
      /usr/lib/libmudflap.so.0(__wrap_main+0x4f) [0x1dc28f]
Nearby object 1: checked region begins 0B into and ends 1B after
mudflap object 0x96711e8: name=`test_44.c:1:13 onbss'
bounds=[0x80c9c40,0x80c9cbf] size=128 area=static check=3r/0w liveness=3
alloc time=1317740344.659190 pc=0x1dc22d
number of nearby objects: 1
*******
mudflap violation 2 (check/read): time=1317740344.696388 ptr=0xbfbfba38 size=129
pc=0x1dca8d location=`test_44.c:9:2 (main)'
      /usr/lib/libmudflap.so.0(__mf_check+0x3d) [0x1dca8d]
      ./testflap(main+0x1c0) [0x80488b4]
      /usr/lib/libmudflap.so.0(__wrap_main+0x4f) [0x1dc28f]
Nearby object 1: checked region begins 0B into and ends 1B after
mudflap object 0x9672110: name=`test_44.c:5:7 (main) onstack'
bounds=[0xbfbfba38,0xbfbfbab7] size=128 area=stack check=3r/0w liveness=3
alloc time=1317740344.659339 pc=0x1dc22d
number of nearby objects: 1