当我运行我的（C ++）程序时，它会因此错误而崩溃。
*检测到glibc * ./load：双重免费或损坏（！prev）： 0x0000000000c6ed50 ***
如何追踪错误？
我尝试使用print（std::cout）语句，但没有成功。 gdb可以让这更容易吗？
答案 0 :(得分：51)
如果您正在使用glibc，则可以将MALLOC_CHECK_环境变量设置为2，这将导致glibc使用malloc的容错版本，这将导致您的程序在完成双重免费的时间点中止。
您可以在运行程序之前使用set environment MALLOC_CHECK_ 2命令从gdb设置此项;该程序应该中止，并在回溯中显示free()调用。
有关详细信息，请参阅man page for malloc()
答案 1 :(得分：23)
至少有两种可能的情况：
对于第一个，我强烈建议对所有删除的指针进行NULL处理。
您有三种选择：
答案 2 :(得分：19)
你可以使用gdb，但我会首先尝试Valgrind。请参阅quick start guide。
简而言之，Valgrind会对您的程序进行检测，以便在使用动态分配的内存时可以检测到多种错误，例如双重释放和写入已分配的内存块末尾（可能会损坏堆）。它会在发生错误时立即检测并报告错误，从而直接指出问题的原因。
答案 3 :(得分：17)
三个基本规则：
NULL NULL。NULL的指针。这三项作品的结合非常好。
答案 4 :(得分：14)
您可以使用valgrind进行调试。
#include<stdio.h>
#include<stdlib.h>
int main()
{
char *x = malloc(100);
free(x);
free(x);
return 0;
}
[sand@PS-CNTOS-64-S11 testbox]$ vim t1.c
[sand@PS-CNTOS-64-S11 testbox]$ cc -g t1.c -o t1
[sand@PS-CNTOS-64-S11 testbox]$ ./t1
*** glibc detected *** ./t1: double free or corruption (top): 0x00000000058f7010 ***
======= Backtrace: =========
/lib64/libc.so.6[0x3a3127245f]
/lib64/libc.so.6(cfree+0x4b)[0x3a312728bb]
./t1[0x400500]
/lib64/libc.so.6(__libc_start_main+0xf4)[0x3a3121d994]
./t1[0x400429]
======= Memory map: ========
00400000-00401000 r-xp 00000000 68:02 30246184 /home/sand/testbox/t1
00600000-00601000 rw-p 00000000 68:02 30246184 /home/sand/testbox/t1
058f7000-05918000 rw-p 058f7000 00:00 0 [heap]
3a30e00000-3a30e1c000 r-xp 00000000 68:03 5308733 /lib64/ld-2.5.so
3a3101b000-3a3101c000 r--p 0001b000 68:03 5308733 /lib64/ld-2.5.so
3a3101c000-3a3101d000 rw-p 0001c000 68:03 5308733 /lib64/ld-2.5.so
3a31200000-3a3134e000 r-xp 00000000 68:03 5310248 /lib64/libc-2.5.so
3a3134e000-3a3154e000 ---p 0014e000 68:03 5310248 /lib64/libc-2.5.so
3a3154e000-3a31552000 r--p 0014e000 68:03 5310248 /lib64/libc-2.5.so
3a31552000-3a31553000 rw-p 00152000 68:03 5310248 /lib64/libc-2.5.so
3a31553000-3a31558000 rw-p 3a31553000 00:00 0
3a41c00000-3a41c0d000 r-xp 00000000 68:03 5310264 /lib64/libgcc_s-4.1.2-20080825.so.1
3a41c0d000-3a41e0d000 ---p 0000d000 68:03 5310264 /lib64/libgcc_s-4.1.2-20080825.so.1
3a41e0d000-3a41e0e000 rw-p 0000d000 68:03 5310264 /lib64/libgcc_s-4.1.2-20080825.so.1
2b1912300000-2b1912302000 rw-p 2b1912300000 00:00 0
2b191231c000-2b191231d000 rw-p 2b191231c000 00:00 0
7ffffe214000-7ffffe229000 rw-p 7ffffffe9000 00:00 0 [stack]
7ffffe2b0000-7ffffe2b4000 r-xp 7ffffe2b0000 00:00 0 [vdso]
ffffffffff600000-ffffffffffe00000 ---p 00000000 00:00 0 [vsyscall]
Aborted
[sand@PS-CNTOS-64-S11 testbox]$
[sand@PS-CNTOS-64-S11 testbox]$ vim t1.c
[sand@PS-CNTOS-64-S11 testbox]$ cc -g t1.c -o t1
[sand@PS-CNTOS-64-S11 testbox]$ valgrind --tool=memcheck ./t1
==20859== Memcheck, a memory error detector
==20859== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al.
==20859== Using Valgrind-3.5.0 and LibVEX; rerun with -h for copyright info
==20859== Command: ./t1
==20859==
==20859== Invalid free() / delete / delete[]
==20859== at 0x4A05A31: free (vg_replace_malloc.c:325)
==20859== by 0x4004FF: main (t1.c:8)
==20859== Address 0x4c26040 is 0 bytes inside a block of size 100 free'd
==20859== at 0x4A05A31: free (vg_replace_malloc.c:325)
==20859== by 0x4004F6: main (t1.c:7)
==20859==
==20859==
==20859== HEAP SUMMARY:
==20859== in use at exit: 0 bytes in 0 blocks
==20859== total heap usage: 1 allocs, 2 frees, 100 bytes allocated
==20859==
==20859== All heap blocks were freed -- no leaks are possible
==20859==
==20859== For counts of detected and suppressed errors, rerun with: -v
==20859== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 4 from 4)
[sand@PS-CNTOS-64-S11 testbox]$
[sand@PS-CNTOS-64-S11 testbox]$ valgrind --tool=memcheck --leak-check=full ./t1
==20899== Memcheck, a memory error detector
==20899== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al.
==20899== Using Valgrind-3.5.0 and LibVEX; rerun with -h for copyright info
==20899== Command: ./t1
==20899==
==20899== Invalid free() / delete / delete[]
==20899== at 0x4A05A31: free (vg_replace_malloc.c:325)
==20899== by 0x4004FF: main (t1.c:8)
==20899== Address 0x4c26040 is 0 bytes inside a block of size 100 free'd
==20899== at 0x4A05A31: free (vg_replace_malloc.c:325)
==20899== by 0x4004F6: main (t1.c:7)
==20899==
==20899==
==20899== HEAP SUMMARY:
==20899== in use at exit: 0 bytes in 0 blocks
==20899== total heap usage: 1 allocs, 2 frees, 100 bytes allocated
==20899==
==20899== All heap blocks were freed -- no leaks are possible
==20899==
==20899== For counts of detected and suppressed errors, rerun with: -v
==20899== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 4 from 4)
[sand@PS-CNTOS-64-S11 testbox]$
一种可能的解决办法：
#include<stdio.h>
#include<stdlib.h>
int main()
{
char *x = malloc(100);
free(x);
x=NULL;
free(x);
return 0;
}
[sand@PS-CNTOS-64-S11 testbox]$ vim t1.c
[sand@PS-CNTOS-64-S11 testbox]$ cc -g t1.c -o t1
[sand@PS-CNTOS-64-S11 testbox]$ ./t1
[sand@PS-CNTOS-64-S11 testbox]$
[sand@PS-CNTOS-64-S11 testbox]$ valgrind --tool=memcheck --leak-check=full ./t1
==20958== Memcheck, a memory error detector
==20958== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al.
==20958== Using Valgrind-3.5.0 and LibVEX; rerun with -h for copyright info
==20958== Command: ./t1
==20958==
==20958==
==20958== HEAP SUMMARY:
==20958== in use at exit: 0 bytes in 0 blocks
==20958== total heap usage: 1 allocs, 1 frees, 100 bytes allocated
==20958==
==20958== All heap blocks were freed -- no leaks are possible
==20958==
==20958== For counts of detected and suppressed errors, rerun with: -v
==20958== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 4 from 4)
[sand@PS-CNTOS-64-S11 testbox]$
使用Valgrind Link
查看博客答案 5 :(得分：5)
使用现代C ++编译器，您可以使用清洁剂进行跟踪。
示例示例：
我的节目：
$cat d_free.cxx
#include<iostream>
using namespace std;
int main()
{
int * i = new int();
delete i;
//i = NULL;
delete i;
}
使用地址清理程序进行编译：
# g++-7.1 d_free.cxx -Wall -Werror -fsanitize=address -g
执行：
# ./a.out
=================================================================
==4836==ERROR: AddressSanitizer: attempting double-free on 0x602000000010 in thread T0:
#0 0x7f35b2d7b3c8 in operator delete(void*, unsigned long) /media/sf_shared/gcc-7.1.0/libsanitizer/asan/asan_new_delete.cc:140
#1 0x400b2c in main /media/sf_shared/jkr/cpp/d_free/d_free.cxx:11
#2 0x7f35b2050c04 in __libc_start_main (/lib64/libc.so.6+0x21c04)
#3 0x400a08 (/media/sf_shared/jkr/cpp/d_free/a.out+0x400a08)
0x602000000010 is located 0 bytes inside of 4-byte region [0x602000000010,0x602000000014)
freed by thread T0 here:
#0 0x7f35b2d7b3c8 in operator delete(void*, unsigned long) /media/sf_shared/gcc-7.1.0/libsanitizer/asan/asan_new_delete.cc:140
#1 0x400b1b in main /media/sf_shared/jkr/cpp/d_free/d_free.cxx:9
#2 0x7f35b2050c04 in __libc_start_main (/lib64/libc.so.6+0x21c04)
previously allocated by thread T0 here:
#0 0x7f35b2d7a040 in operator new(unsigned long) /media/sf_shared/gcc-7.1.0/libsanitizer/asan/asan_new_delete.cc:80
#1 0x400ac9 in main /media/sf_shared/jkr/cpp/d_free/d_free.cxx:8
#2 0x7f35b2050c04 in __libc_start_main (/lib64/libc.so.6+0x21c04)
SUMMARY: AddressSanitizer: double-free /media/sf_shared/gcc-7.1.0/libsanitizer/asan/asan_new_delete.cc:140 in operator delete(void*, unsigned long)
==4836==ABORTING
答案 6 :(得分：4)
您使用的是智能指针，例如Boost shared_ptr吗？如果是这样，请通过调用get()检查您是否在任何地方直接使用原始指针。我发现这是一个非常普遍的问题。
例如，想象一下将原始指针传递给代码的场景（可能作为回调处理程序）。您可能决定将其分配给智能指针以应对引用计数等。大错误：除非您采用深层复制，否则您的代码不会拥有此指针。当您的代码使用智能指针完成时，它将销毁它并尝试销毁它指向的内存，因为它认为没有其他人需要它，但是调用然后代码将尝试删除它，你将获得双重免费问题。
当然，这可能不是你的问题。这里最简单的是一个展示它如何发生的例子。第一次删除很好，但编译器检测到它已经删除了该内存并导致问题。这就是为什么在删除后立即为指针赋值0是个好主意。
int main(int argc, char* argv[])
{
char* ptr = new char[20];
delete[] ptr;
ptr = 0; // Comment me out and watch me crash and burn.
delete[] ptr;
}
编辑：将delete更改为delete[]，因为ptr是一个char数组。
答案 7 :(得分：-2)
我知道这是一个非常古老的主题，但它是谷歌搜索此错误的最佳人选，并且没有一个回复提到错误的常见原因。
关闭您已关闭的文件。
如果您没有注意并且有两个不同的功能关闭同一个文件，那么第二个将产生此错误。