Question

我有一个用c编写的程序，它在bash中运行良好，但在valgrind下给出了奇怪的结果，而valgrind报告内存泄漏。

在bash中运行：

：〜/ sandbox / binofino $ ./a.out

24 = 3 + 21   
24 = 3 + 21   
24 = 3 + 8 + 13   
24 = 1 + 2 + 8 + 13   
24 = 1 + 2 + 3 + 5 + 13   
24 = 1 + 2 + 21

在valgrind下：

>:~/sandbox/binofino$ valgrind ./a.out
==20116== Memcheck, a memory error detector
==20116== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al.
==20116== Using Valgrind-3.6.0.SVN-Debian and LibVEX; rerun with -h for copyright info
==20116== Command: ./a.out
==20116== 
==20116== Invalid read of size 4
==20116==    at 0x804857A: main (in /home/..../sandbox/binofino/a.out)
==20116==  Address 0x41a402c is 0 bytes after a block of size 4 free'd
==20116==    at 0x4025016: realloc (vg_replace_malloc.c:525)
==20116==    by 0x804879F: get_fibo_index (in /home/..../sandbox/binofino/a.out)
==20116==    by 0x804854F: main (in /home/..../sandbox/binofino/a.out)
==20116== 
24 = 1 + 1   
==20116== Invalid read of size 4
==20116==    at 0x80485CE: main (in /home/..../sandbox/binofino/a.out)
==20116==  Address 0x41a402c is 0 bytes after a block of size 4 free'd
==20116==    at 0x4025016: realloc (vg_replace_malloc.c:525)
==20116==    by 0x804879F: get_fibo_index (in /home/..../sandbox/binofino/a.out)
==20116==    by 0x804854F: main (in /home/..../sandbox/binofino/a.out)
==20116== 
24 = 1   
==20116== Invalid free() / delete / delete[]
==20116==    at 0x4024B3A: free (vg_replace_malloc.c:366)
==20116==    by 0x804867E: main (in /home/..../sandbox/binofino/a.out)
==20116==  Address 0x41a4028 is 0 bytes inside a block of size 4 free'd
==20116==    at 0x4025016: realloc (vg_replace_malloc.c:525)
==20116==    by 0x804879F: get_fibo_index (in /home/..../sandbox/binofino/a.out)
==20116==    by 0x804854F: main (in /home/..../sandbox/binofino/a.out)
==20116== 
==20116== 
==20116== HEAP SUMMARY:
==20116==     in use at exit: 8 bytes in 1 blocks
==20116==   total heap usage: 4 allocs, 4 frees, 20 bytes allocated
==20116== 
==20116== LEAK SUMMARY:
==20116==    definitely lost: 8 bytes in 1 blocks
==20116==    indirectly lost: 0 bytes in 0 blocks
==20116==      possibly lost: 0 bytes in 0 blocks
==20116==    still reachable: 0 bytes in 0 blocks
==20116==         suppressed: 0 bytes in 0 blocks
==20116== Rerun with --leak-check=full to see details of leaked memory
==20116== 
==20116== For counts of detected and suppressed errors, rerun with: -v
==20116== ERROR SUMMARY: 5 errors from 3 contexts (suppressed: 11 from 6)

它不仅报告内存泄漏，还报告错误，程序的输出完全错误。

为什么？

Answer 1

因为你有一个错误（实际上有几个错误）。

特别是，在get_fibo_index中你realloc有一些内存，然后在main中读取超出分配缓冲区的末尾（产生完全未定义的结果）。

使用-g重建您的程序，在Valgrind下重新运行它，并修复它找到的所有“无效”错误。

（使用-g重建将为您提供文件和行信息，以便更轻松地修复错误。）

程序在bash中运行良好但不与valgrind一起运行

1 个答案: