使用valgrind检测c程序内存泄漏，数组越界，非法指针，重复free等问题

一、valgrind的安装（Ubuntu）

sudo apt install valgrind  //安装

 valgrind --version //安装完检查版本信息确认

二、检测内存泄漏

例子：mem.c

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


int main()
{
      char *ptr;
      ptr = (char *)malloc(10);
       
      return 0;
}

执行

gcc -o mem mem.c -g

valgrind --tool=memcheck ./mem

打印信息：

==47084== Memcheck, a memory error detector
==47084== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==47084== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==47084== Command: ./mem
==47084== 
==47084== 
==47084== HEAP SUMMARY:
==47084==     in use at exit: 10 bytes in 1 blocks  //指示在程序退出时，还有多少内存没有释放
==47084==   total heap usage: 1 allocs, 0 frees, 10 bytes allocated // 指示该执行过程malloc和free调用的次数
==47084== 
==47084== LEAK SUMMARY:
==47084==    definitely lost: 10 bytes in 1 blocks
==47084==    indirectly lost: 0 bytes in 0 blocks
==47084==      possibly lost: 0 bytes in 0 blocks
==47084==    still reachable: 0 bytes in 0 blocks
==47084==         suppressed: 0 bytes in 0 blocks
==47084== Rerun with --leak-check=full to see details of leaked memory
==47084== 
==47084== For counts of detected and suppressed errors, rerun with: -v
==47084== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
 

查看具体的泄漏位置，执行

valgrind --leak-check=full ./mem

打印信息：

==47152== Memcheck, a memory error detector
==47152== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==47152== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==47152== Command: ./mem
==47152== 
==47152== 
==47152== HEAP SUMMARY:
==47152==     in use at exit: 10 bytes in 1 blocks
==47152==   total heap usage: 1 allocs, 0 frees, 10 bytes allocated
==47152== 
==47152== 10 bytes in 1 blocks are definitely lost in loss record 1 of 1
==47152==    at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) //malloc函数
==47152==    by 0x10865B: main (mem.c:10)  //第10行
==47152== 
==47152== LEAK SUMMARY:
==47152==    definitely lost: 10 bytes in 1 blocks
==47152==    indirectly lost: 0 bytes in 0 blocks
==47152==      possibly lost: 0 bytes in 0 blocks
==47152==    still reachable: 0 bytes in 0 blocks
==47152==         suppressed: 0 bytes in 0 blocks
==47152== 
==47152== For counts of detected and suppressed errors, rerun with: -v
==47152== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
 

三、检测其他

例子：mem.c

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

int main(void)
{
    char *ptr = malloc(10);
    ptr[12] = 'a'; // 数组越界
    free(ptr); 
    free(ptr);// 重复释放
    char *p1;
    *p1 = '1'; // 非法指针
    return 0;
}

执行

valgrind --tool=memcheck ./mem

打印信息：

==47294== Memcheck, a memory error detector
==47294== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==47294== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==47294== Command: ./mem
//提示堆数组越界
==47294== Invalid write of size 1    
==47294==    at 0x108787: main (mem.c:8)
==47294==  Address 0x522d04c is 2 bytes after a block of size 10 alloc'd
==47294==    at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==47294==    by 0x10877A: main (mem.c:7)
//提示重复释放
==47294== Invalid free() / delete / delete[] / realloc()  
==47294==    at 0x4C30D3B: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==47294==    by 0x1087C1: main (mem.c:13)
==47294==  Address 0x522d040 is 0 bytes inside a block of size 10 free'd
==47294==    at 0x4C30D3B: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==47294==    by 0x1087B5: main (mem.c:12)
==47294==  Block was alloc'd at
==47294==    at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==47294==    by 0x10877A: main (mem.c:7)
//提示非法指针
==47294== Use of uninitialised value of size 8
==47294==    at 0x1087C6: main (mem.c:15)
==47294== 
==47294== 
==47294== Process terminating with default action of signal 11 (SIGSEGV)
==47294==  Bad permissions for mapped region at address 0x1087F0
==47294==    at 0x1087C6: main (mem.c:15)
==47294== 
==47294== HEAP SUMMARY:
==47294==     in use at exit: 0 bytes in 0 blocks
==47294==   total heap usage: 1 allocs, 2 frees, 10 bytes allocated
==47294== 
==47294== All heap blocks were freed -- no leaks are possible
==47294== 
==47294== For counts of detected and suppressed errors, rerun with: -v
==47294== Use --track-origins=yes to see where uninitialised values come from
==47294== ERROR SUMMARY: 3 errors from 3 contexts (suppressed: 0 from 0)
段错误 (核心已转储)

更多错误提示及例子可参考这篇博客：https://blog.youkuaiyun.com/u010168781/article/details/83749609