下面是一段有问题的C程序代码test.c
#include <stdlib.h>void f(void)
{
int* x = malloc(10 * sizeof(int));
x[10] = 0; //问题1: 数组下标越界
} //问题2: 内存没有释放int main(void)
{
f();
return 0;
}1、 编译程序test.c
gcc -Wall test.c -g -o test
2、 使用Valgrind检查程序BUG
valgrind --tool=memcheck --leak-check=full ./test
3、 分析输出的调试信息
==3908== Memcheck, a memory error detector.
==3908== Copyright (C) 2002-2007, and GNU GPL'd, by Julian Seward et al.
==3908== Using LibVEX rev 1732, a library for dynamic binary translation.
==3908== Copyright (C) 2004-2007, and GNU GPL'd, by OpenWorks LLP.
==3908== Using valgrind-3.2.3, a dynamic binary instrumentation framework.
==3908== Copyright (C) 2000-2007, and GNU GPL'd, by Julian Seward et al.
==3908== For more details, rerun with: -v
==3908==
--3908-- DWARF2 CFI reader: unhandled CFI instruction 0:50
--3908-- DWARF2 CFI reader: unhandled CFI instruction 0:50
/*数组越界错误*/
==3908== Invalid write of size 4
==3908== at 0x8048384: f (test.c:6)
==3908== by 0x80483AC: main (test.c:11)
==3908== Address 0x400C050 is 0 bytes after a block of size 40 alloc'd
==3908== at 0x40046F2: malloc (vg_replace_malloc.c:149)
==3908== by 0x8048377: f (test.c:5)
==3908== by 0x80483AC: main (test.c:11)
==3908==
==3908== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 14 from 1)
==3908== malloc/free: in use at exit: 40 bytes in 1 blocks.
==3908== malloc/free: 1 allocs, 0 frees, 40 bytes allocated.
==3908== For counts of detected errors, rerun with: -v
==3908== searching for pointers to 1 not-freed blocks.
==3908== checked 59,124 bytes.
==3908==
==3908==
/*有内存空间没有释放*/
==3908== 40 bytes in 1 blocks are definitely lost in loss record 1 of 1
==3908== at 0x40046F2: malloc (vg_replace_malloc.c:149)
==3908== by 0x8048377: f (test.c:5)
==3908== by 0x80483AC: main (test.c:11)
==3908==
==3908== LEAK SUMMARY:
==3908== definitely lost: 40 bytes in 1 blocks.
==3908== possibly lost: 0 bytes in 0 blocks.
==3908== still reachable: 0 bytes in 0 blocks.
==3908== suppressed: 0 bytes in 0 blocks