Commit message: CVE-2017-13000/IEEE 802.15.4: Fix bug introduced two fixes prior.

We've already advanced the pointer past the PAN ID, if present; it now
points to the address, so don't add 2 to it.

This fixes a buffer over-read discovered by Forcepoint's security
researchers Otto Airamo & Antti Levomäki.

Add a test using the capture file supplied by the reporter(s).
CVE: CVE-2017-13000
CWE: CWE-125
Vulnerability description: The IEEE 802.15.4 parser in tcpdump before 4.9.2 has a buffer over-read in print-802_15_4.c:ieee802_15_4_if_print().

Project: tcpdump
File: print-802_15_4.c

ieee802_15_4_if_print(netdissect_options *ndo,
                      const struct pcap_pkthdr *h, const u_char *p)
{
	u_int caplen = h->caplen;
	u_int hdrlen;
	uint16_t fc;
	uint8_t seq;
	uint16_t panid = 0;

	if (caplen < 3) {
		ND_PRINT((ndo, "[|802.15.4]"));
		return caplen;
	}
	hdrlen = 3;

	fc = EXTRACT_LE_16BITS(p);
	seq = EXTRACT_LE_8BITS(p + 2);

	p += 3;
	caplen -= 3;

	ND_PRINT((ndo,"IEEE 802.15.4 %s packet ", ftypes[FC_FRAME_TYPE(fc)]));
	if (ndo->ndo_vflag)
		ND_PRINT((ndo,"seq %02x ", seq));

	/*
	 * Destination address and PAN ID, if present.
	 */
	switch (FC_DEST_ADDRESSING_MODE(fc)) {
	case FC_ADDRESSING_MODE_NONE:
		if (fc & FC_PAN_ID_COMPRESSION) {
			/*
			 * PAN ID compression; this requires that both
			 * the source and destination addresses be present,
			 * but the destination address is missing.
			 */
			ND_PRINT((ndo, "[|802.15.4]"));
			return hdrlen;
		}
		if (ndo->ndo_vflag)
			ND_PRINT((ndo,"none "));
		break;
	case FC_ADDRESSING_MODE_RESERVED:
		if (ndo->ndo_vflag)
			ND_PRINT((ndo,"reserved destination addressing mode"));
		return hdrlen;
	case FC_ADDRESSING_MODE_SHORT:
		if (caplen < 2) {
			ND_PRINT((ndo, "[|802.15.4]"));
			return hdrlen;
		}
		panid = EXTRACT_LE_16BITS(p);
		p += 2;
		caplen -= 2;
		hdrlen += 2;
		if (caplen < 2) {
			ND_PRINT((ndo, "[|802.15.4]"));
 			return hdrlen;
 		}
 		if (ndo->ndo_vflag)
			ND_PRINT((ndo,"%04x:%04x ", panid, EXTRACT_LE_16BITS(p + 2)));
 		p += 2;
 		caplen -= 2;
 		hdrlen += 2;
		break;
	case FC_ADDRESSING_MODE_LONG:
		if (caplen < 2) {
			ND_PRINT((ndo, "[|802.15.4]"));
			return hdrlen;
		}
		panid = EXTRACT_LE_16BITS(p);
		p += 2;
		caplen -= 2;
		hdrlen += 2;
		if (caplen < 8) {
			ND_PRINT((ndo, "[|802.15.4]"));
			return hdrlen;
		}
		if (ndo->ndo_vflag)
			ND_PRINT((ndo,"%04x:%s ", panid, le64addr_string(ndo, p)));
		p += 8;
		caplen -= 8;
		hdrlen += 8;
		break;
	}
	if (ndo->ndo_vflag)
		ND_PRINT((ndo,"< "));

	/*
	 * Source address and PAN ID, if present.
	 */
	switch (FC_SRC_ADDRESSING_MODE(fc)) {
	case FC_ADDRESSING_MODE_NONE:
		if (ndo->ndo_vflag)
			ND_PRINT((ndo,"none "));
		break;
	case FC_ADDRESSING_MODE_RESERVED:
		if (ndo->ndo_vflag)
			ND_PRINT((ndo,"reserved source addressing mode"));
		return 0;
	case FC_ADDRESSING_MODE_SHORT:
		if (!(fc & FC_PAN_ID_COMPRESSION)) {
			/*
			 * The source PAN ID is not compressed out, so
			 * fetch it.  (Otherwise, we'll use the destination
			 * PAN ID, fetched above.)
			 */
			if (caplen < 2) {
				ND_PRINT((ndo, "[|802.15.4]"));
				return hdrlen;
			}
			panid = EXTRACT_LE_16BITS(p);
			p += 2;
			caplen -= 2;
			hdrlen += 2;
		}
		if (caplen < 2) {
			ND_PRINT((ndo, "[|802.15.4]"));
			return hdrlen;
		}
		if (ndo->ndo_vflag)
			ND_PRINT((ndo,"%04x:%04x ", panid, EXTRACT_LE_16BITS(p)));
		p += 2;
		caplen -= 2;
		hdrlen += 2;
		break;
	case FC_ADDRESSING_MODE_LONG:
		if (!(fc & FC_PAN_ID_COMPRESSION)) {
			/*
			 * The source PAN ID is not compressed out, so
			 * fetch it.  (Otherwise, we'll use the destination
			 * PAN ID, fetched above.)
			 */
			if (caplen < 2) {
				ND_PRINT((ndo, "[|802.15.4]"));
				return hdrlen;
			}
			panid = EXTRACT_LE_16BITS(p);
			p += 2;
			caplen -= 2;
			hdrlen += 2;
		}
		if (caplen < 8) {
			ND_PRINT((ndo, "[|802.15.4]"));
			return hdrlen;
		}
		if (ndo->ndo_vflag)
			ND_PRINT((ndo,"%04x:%s ", panid, le64addr_string(ndo, p)));
		p += 8;
		caplen -= 8;
		hdrlen += 8;
		break;
	}

	if (!ndo->ndo_suppress_default_print)
		ND_DEFAULTPRINT(p, caplen);

	return hdrlen;
}