static size_t all_data_cb(const void *ptr, size_t size, size_t nmemb,
			  void *user_data)
{
	struct data_buffer *db = (struct data_buffer *)user_data;
	size_t len = size * nmemb;
	size_t oldlen, newlen;
	void *newmem;
	static const unsigned char zero = 0;

	oldlen = db->len;
	newlen = oldlen + len;

	newmem = realloc(db->buf, newlen + 1);
	if (!newmem)
		return 0;

	db->buf = newmem;
	db->len = newlen;
	memcpy((uint8_t*)db->buf + oldlen, ptr, len);
	memcpy((uint8_t*)db->buf + newlen, &zero, 1);	/* null terminate */

	return len;
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.