c - 内存泄漏Valgrind

我写了一个程序把一个字符串五乘五分成块。这是我的节目。

struct list
{
    char *str;
    struct list* next;
};

struct list* head = NULL;

void insert(char *cont)
{
    struct list* temp = (struct list*)malloc(sizeof(struct list));

    size_t len = strlen(cont);
    char *heapString = (char*)malloc(len);
    strcpy(heapString,cont);

    temp->str = heapString;
    temp->next = NULL;

    if(head == NULL)
    {
        head = temp;
        return ;
    }

    temp->next = head;
    head = temp;
}
void print()
{
    struct list* temp = head;
    while(temp != NULL)
    {
        printf("%s\n",temp->str);
        temp = temp->next;
    }
}
void clearmem()
{
    struct list* temp = head;
    while(temp != NULL)
    {
        free(temp->str);
        free(temp);
        temp = temp->next;
    }
}
int main()
{
    char text[] = "abcdefghijklmno";
    size_t len = strlen(text);
    while(len !=0)
    {
        char *temp;
        temp = text ;
        temp = temp + len - 5;

        insert(temp);
        *(text+len-5) = '\0';
        len = strlen(text);
        free(temp);
    }
    print();
    clearmem();
}

我的程序运行良好。但是当我试图通过valgrind运行这个程序时，我得到了以下消息。上面说有12个错误。

==2055== Invalid write of size 1
==2055==    at 0x4C32E0D: strcpy (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2055==    by 0x10888C: insert (in /home/infant/Documents/Sample_codes/a.out)
==2055==    by 0x1089BD: main (in /home/infant/Documents/Sample_codes/a.out)
==2055==  Address 0x522d095 is 0 bytes after a block of size 5 alloc'd
==2055==    at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2055==    by 0x108875: insert (in /home/infant/Documents/Sample_codes/a.out)
==2055==    by 0x1089BD: main (in /home/infant/Documents/Sample_codes/a.out)
==2055==
==2055== Invalid free() / delete / delete[] / realloc()
==2055==    at 0x4C30D3B: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2055==    by 0x1089EB: main (in /home/infant/Documents/Sample_codes/a.out)
==2055==  Address 0x1fff00030a is on thread 1's stack
==2055==  in frame #1, created by main (???:)
==2055==
==2055== Invalid read of size 1
==2055==    at 0x4C32D44: __strlen_sse2 (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2055==    by 0x4EBC9D1: puts (ioputs.c:35)
==2055==    by 0x1088FC: print (in /home/infant/Documents/Sample_codes/a.out)
==2055==    by 0x1089FC: main (in /home/infant/Documents/Sample_codes/a.out)
==2055==  Address 0x522d1d5 is 0 bytes after a block of size 5 alloc'd
==2055==    at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2055==    by 0x108875: insert (in /home/infant/Documents/Sample_codes/a.out)
==2055==    by 0x1089BD: main (in /home/infant/Documents/Sample_codes/a.out)
==2055==
abcde
fghij
klmno
==2055== Invalid read of size 8
==2055==    at 0x108947: clearmem (in /home/infant/Documents/Sample_codes/a.out)
==2055==    by 0x108A06: main (in /home/infant/Documents/Sample_codes/a.out)
==2055==  Address 0x522d188 is 8 bytes inside a block of size 16 free'd
==2055==    at 0x4C30D3B: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2055==    by 0x108942: clearmem (in /home/infant/Documents/Sample_codes/a.out)
==2055==    by 0x108A06: main (in /home/infant/Documents/Sample_codes/a.out)
==2055==  Block was alloc'd at
==2055==    at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2055==    by 0x108855: insert (in /home/infant/Documents/Sample_codes/a.out)
==2055==    by 0x1089BD: main (in /home/infant/Documents/Sample_codes/a.out)
==2055==
==2055==
==2055== HEAP SUMMARY:
==2055==     in use at exit: 0 bytes in 0 blocks
==2055==   total heap usage: 7 allocs, 10 frees, 1,087 bytes allocated
==2055==
==2055== All heap blocks were freed -- no leaks are possible
==2055==
==2055== For counts of detected and suppressed errors, rerun with: -v
==2055== ERROR SUMMARY: 12 errors from 4 contexts (suppressed: 0 from 0)

即使我清除了堆中的所有内存，我还是从4个上下文中得到了12个错误。我的错误是什么？

最佳答案

一步一步地。
Invalid write of size 1
您的malloc()不会为字符串结束符分配空间，但strcpy()会尝试写入它。使用

char *heapString = malloc(len + 1);

相反。（注：no need to castvoid*至char*！）。为了简单起见，您也可以尝试使用（非标准）strdup(cont)。
Invalid free() / delete / delete[] / realloc()
您的temp指向char中的text。使用free()是没有意义的，因为这里没有分配任何内容。取消那个电话。
Invalid read of size 1
这应该与第一个错误有关。值得注意的是，在print()中，如何在编译时将printf("%s\n",temp->str)转换为（更快的）puts(temp->str)。这就是为什么valgrind抱怨有人打电话给puts。
Invalid read of size 8
在

free(temp);
temp = temp->next;

你在它被释放后阅读。

关于c - 内存泄漏Valgrind，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/53008227/

invalid

c - 内存泄漏Valgrind