cJSON *cJSON_Duplicate(cJSON *item,int recurse)
{
	cJSON *newitem,*cptr,*nptr=0,*newchild;
	/* Bail on bad ptr */
	if (!item) return 0;
	/* Create new item */
	newitem=cJSON_New_Item();
	if (!newitem) return 0;
	/* Copy over all vars */
	newitem->type=item->type&(~cJSON_IsReference),newitem->valueint=item->valueint,newitem->valuedouble=item->valuedouble;
	if (item->valuestring)	{newitem->valuestring=cJSON_strdup(item->valuestring);	if (!newitem->valuestring)	{cJSON_Delete(newitem);return 0;}}
	if (item->string)		{newitem->string=cJSON_strdup(item->string);			if (!newitem->string)		{cJSON_Delete(newitem);return 0;}}
	/* If non-recursive, then we're done! */
	if (!recurse) return newitem;
	/* Walk the ->next chain for the child. */
	cptr=item->child;
	while (cptr)
	{
		newchild=cJSON_Duplicate(cptr,1);		/* Duplicate (with recurse) each item in the ->next chain */
		if (!newchild) {cJSON_Delete(newitem);return 0;}
		if (nptr)	{nptr->next=newchild,newchild->prev=nptr;nptr=newchild;}	/* If newitem->child already set, then crosswire ->prev and ->next and move on */
		else		{newitem->child=newchild;nptr=newchild;}					/* Set newitem->child and move to it */
		cptr=cptr->next;
	}
	return newitem;
}
The program copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow.