ping reads raw IP packets from the network to process responses in the prpack() function. As part of processing a response ping has to reconstruct the IP header, the ICMP header and if present a "quoted packet," which represents the packet that generated an ICMP error. The quoted packet again has an IP header and an ICMP header. The prpack() copies received IP and ICMP headers into stack buffers for further processing. In so doing, it fails to take into account the possible presence of IP option headers following the IP header in either the response or the quoted packet. When IP options are present, pr_pack() overflows the destination buffer by up to 40 bytes.