需要 Valgrind 输出解释协助

Question

我是 C 编程的新手，有人要求我检查 linux 实用程序是否存在缓冲区溢出，但是我对这方面的了解有限，所以请原谅我做得不好在它。我使用 Valgrind 来检测溢出，并且在其中我收到了一个明确的泄漏，所以我应用了 --leak-check-full 来确定泄漏可能来自哪里，但是我'我不确定我该如何进行，有人可以帮助我吗？

我选择的实用程序是 nstat。这是我的结果：

  valgrind --leak-check=full nstat -d 1111111111                        
                                               
==3749== Memcheck, a memory error detector                             
==3749== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.      
==3749== Using Valgrind-3.15.0 and LibVEX; rerun with -h for copyright info        
==3749== Command: nstat -d 1111111111        
==3749==                        
#kernel                        
IpInReceives                    112                0.0   
IpInDelivers                    112                0.0     
IpOutRequests                   115                0.0    
TcpActiveOpens                  6                  0.0     
TcpInSegs                       30                 0.0    
TcpOutSegs                      32                 0.0    
TcpRetransSegs                  1                  0.0    
UdpInDatagrams                  82                 0.0    
UdpOutDatagrams                 82                 0.0      
Ip6InReceives                   2                  0.0      
Ip6InDelivers                   2                  0.0     
Ip6OutRequests                  2                  0.0      
Ip6OutNoRoutes                  2                  0.0      
Ip6InMcastPkts                  2                  0.0       
Ip6OutMcastPkts                 2                  0.0      
Ip6InOctets                     186                0.0      
Ip6OutOctets                    186                0.0       
Ip6InMcastOctets                186                0.0       
Ip6OutMcastOctets               186                0.0       
Ip6InNoECTPkts                  2                  0.0        
Udp6InDatagrams                 2                  0.0        
Udp6OutDatagrams                2                  0.0        
TcpExtTW                        2                  0.0        
TcpExtTCPHPHits                 6                  0.0         
TcpExtTCPPureAcks               5                  0.0        
TcpExtTCPHPAcks                 6                  0.0      
TcpExtTCPTimeouts               1                  0.0      
TcpExtTCPSynRetrans             1                  0.0     
TcpExtTCPOrigDataSent           12                 0.0     
TcpExtTCPDelivered              18                 0.0     
IpExtInMcastPkts                4                  0.0     
IpExtOutMcastPkts               4                  0.0      
IpExtInOctets                   10138              0.0      
IpExtOutOctets                  9060               0.0      
IpExtInMcastOctets              292                0.0       
IpExtOutMcastOctets             292                0.0        
IpExtInNoECTPkts                112                0.0       
==3749==      
==3749== HEAP SUMMARY:     
==3749==     in use at exit: 18,429 bytes in 725 blocks      
==3749==   total heap usage: 756 allocs, 31 frees, 34,350 bytes allocated     
==3749==       
==3749== 128 bytes in 1 blocks are definitely lost in loss record 1 of 9        
==3749==    at 0x483B7F3: malloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)       
==3749==    by 0x10C79D: ??? (in /usr/bin/nstat)          
==3749==    by 0x4BE00B2: (below main) (libc-start.c:308)           
==3749==              
==3749== LEAK SUMMARY:             
==3749==    definitely lost: 128 bytes in 1 blocks         
==3749==    indirectly lost: 0 bytes in 0 blocks            
==3749==      possibly lost: 0 bytes in 0 blocks           
==3749==    still reachable: 18,301 bytes in 724 blocks            
==3749==         suppressed: 0 bytes in 0 blocks          
==3749== Reachable blocks (those to which a pointer was found) are not shown.      
==3749== To see them, rerun with: --leak-check=full --show-leak-kinds=all      
==3749==                       
==3749== For lists of detected and suppressed errors, rerun with: -s          
==3749== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

我在 Valgrind 手册上搜索过类似的输出结果，但没有找到。如果有人能告诉我如何继续我的分析，那就太好了。

Answer 1

如果您正在检查缓冲区溢出，请放心，泄漏不属于该类别。但是，您的工作还远未完成。您需要考虑两个主要项目。

首先是您的代码覆盖率。仅仅一项测试可能远远不够。理想情况下，您应该有一个完整的测试套件，其中还包含测试覆盖率的度量。

其次，哪个工具最好。 Valgrind memcheck 而不是 做的一件事是检查静态分配变量和全局变量的溢出。动态分配的内存（使用 malloc 或 new）将检查。

为了检查静态分配和全局变量，我建议您使用地址清理器。但是，这将需要重建 nstat.

需要 Valgrind 输出解释协助

Valgrind output interpretation assistance needed

c

valgrind