double free or corruption (fasttop)

Question

The following section of my code gives me this messege when executing * glibc detected ./a.out: double free or corruption (fasttop): 0x08e065d0 **

i have gone through the code many times but i cant clealry see how i am misusing the free (temp2)

bool found= false;
int x=0;
for ( x=0; x<=312500; x++)
{
    while (count <=32)
    {
        fscanf (file, "%d", &temp->num);  

        temp->ptr=NULL;

        newNode = (NODE *)malloc(sizeof(NODE));
        newNode->num=temp->num;
        newNode->ptr=NULL;

        if (first != NULL)
        {
            temp2=(NODE *)malloc(sizeof(NODE));

            temp2=first;
            while (temp2 != NULL && !found)
            {
                if (temp2->num == newNode->num) 
                {found=true;}

                temp2= temp2->ptr;
            }

            free(temp2);

            if (!found)
            { 
                last->ptr=newNode;
                last=newNode;
                count=count+1;
            }   
        }   
        else  
        {
            first = newNode;
            last = newNode;
            count=count+1;
        }

        fflush(stdin);
    }

Answer 1

The problem is here:

        temp2=first;

Basically, when you free temp2, you free first, not the memory allocated here:

        temp2=(NODE *)malloc(sizeof(NODE));

, which remains a memory leak, because after the assignment it can't be freed anymore.

Also, your code has probably some more problems (one is that you shouldn't use fflush on an input stream), but without some more details, it's impossible to tell.