CVE-2017-13050 (Other, published 2017-09-14T06:29Z)
Description: value: The RPKI-Router parser in tcpdump before 4.9.2 has a buffer over-read in print-rpki-rtr.c:rpki_rtr_pdu_print().
Severity: HIGH (CVSS v3 base score: 9.8)
Weakness: CWE-125 \u2014 Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
Repository: https://github.com/the-tcpdump-group/tcpdump
Files changed:
print-rpki-rtr.c
tests/TESTLIST
tests/kday2.out
tests/kday3.out
tests/kday4.out
tests/kday5.out
tests/kday7.out
tests/kday8.out
tests/rpki-rtr-oob.out
Commit message: CVE-2017-13050/RPKI-Router: fix a few bugs

The decoder didn't properly check that the PDU length stored in the PDU
header is correct. The only check in place was in rpki_rtr_print() and it
tested whether the length is zero but that is not sufficient. Make all
necessary length and bounds checks, both generic and type-specific, in
rpki_rtr_pdu_print() and reduce rpki_rtr_print() to a simple loop.

This also fixes a minor bug and PDU type 0 (Serial Notify from RFC 6810
Section 5.2) is valid again.

In rpki_rtr_pdu_print() any protocol version was considered version 0,
fix it to skip the rest of input if the PDU protocol version is unknown.

Ibid, the PDU type 10 (Error Report from RFC 6810 Section 5.10) case
block didn't consider the "Length of Error Text" data element mandatory,
put it right.

Ibid, when printing an encapsulated PDU, give itself (via recursion)
respective buffer length to make it possible to tell whether the
encapsulated PDU fits. Do not recurse deeper than 2nd level.

Update prior RPKI-Router test cases that now stop to decode earlier
because of the stricter checks.

This fixes a buffer over-read discovered by Bhargava Shastry,
SecT/TU Berlin.

Add a test using the capture file supplied by the reporter(s).


Vulnerable code:
static int
rpki_rtr_pdu_print (netdissect_options *ndo, const u_char *tptr, u_int indent)
    ND_TCHECK2(*tptr, pdu_len);
	    ND_TCHECK2(*tptr, encapsulated_pdu_length);
	    tlen = pdu_len;
	    tptr += sizeof(*pdu);
	    tlen -= sizeof(*pdu);

	    /*
	     * Recurse if there is an encapsulated PDU.
	     */
	    if (encapsulated_pdu_length &&
		(encapsulated_pdu_length <= tlen)) {
		ND_PRINT((ndo, "%s-----encapsulated PDU-----", indent_string(indent+4)));
		if (rpki_rtr_pdu_print(ndo, tptr, indent+2))
			goto trunc;
	    tptr += encapsulated_pdu_length;
	    tlen -= encapsulated_pdu_length;
	    text_length = 0;
	    if (tlen > 4) {
		text_length = EXTRACT_32BITS(tptr);
		tptr += 4;
		tlen -= 4;
	    }
	    ND_TCHECK2(*tptr, text_length);
	    if (text_length && (text_length <= tlen )) {
		if (fn_printn(ndo, tptr, text_length, ndo->ndo_snapend))
    return 0;
    return 1;
    u_int tlen, pdu_type, pdu_len;
    const u_char *tptr;
    const rpki_rtr_pdu *pdu_header;

    tptr = pptr;
    tlen = len;


    while (tlen >= sizeof(rpki_rtr_pdu)) {

        ND_TCHECK2(*tptr, sizeof(rpki_rtr_pdu));

	pdu_header = (const rpki_rtr_pdu *)tptr;
        pdu_type = pdu_header->pdu_type;
        pdu_len = EXTRACT_32BITS(pdu_header->length);
        ND_TCHECK2(*tptr, pdu_len);

        /* infinite loop check */
        if (!pdu_type || !pdu_len) {
            break;
        }

        if (tlen < pdu_len) {
            goto trunc;
        }

	/*
	 * Print the PDU.
	 */
	if (rpki_rtr_pdu_print(ndo, tptr, 8))
		goto trunc;

        tlen -= pdu_len;
        tptr += pdu_len;
    return;
trunc:
    ND_PRINT((ndo, "\n\t%s", tstr));
	RPKI-RTRv177, Unknown PDU (100), length: 60
	  0x0000:  b164 003c 0000 003c 0000 00ff ff1f 1b70
	  0x0010:  f857 ee68 4dfd 4d5f d9bd c709 30ac 8176
	  0x0020:  b36d cc11 3abf 1291 f106 4ede 61f4 6297
	  0x0030:  afc4 39a4 0db9 7aa5 6873 33e8
	RPKI-RTRv65, Error Report PDU (10), length: 21
	  Error code: Unknown (66), Encapsulated PDU length: 37
	[|RPKI-RTR]
	RPKI-RTRv177, Unknown PDU (100), length: 60
	  0x0000:  b164 003c 0000 003c 0000 00ff ff1f 1b70
	  0x0010:  f857 ee68 4dfd 4d5f d9bd c709 30ac 8176
	  0x0020:  b36d cc11 3abf 1291 f106 4ede 61f4 6297
	  0x0030:  afc4 39a4 0db9 7aa5 6873 33e8
	RPKI-RTRv65, Error Report PDU (10), length: 66
	[|RPKI-RTR]
	RPKI-RTRv177, Unknown PDU (100), length: 60
	  0x0000:  b164 003c 0000 003c 0000 00ff ff1f 1b70
	  0x0010:  f857 ee68 4dfd 4d5f d9bd c709 30ac 8176
	  0x0020:  b36d cc11 3abf 1291 f106 4ede 61f4 6297
	  0x0030:  afc4 39a4 0db9 7aa5 6873 33e8
	RPKI-RTRv65, Error Report PDU (10), length: 66
	  Error code: Unknown (66), Encapsulated PDU length: 37
	    -----encapsulated PDU-----
	[|RPKI-RTR]
	RPKI-RTRv177, Unknown PDU (100), length: 60
	  0x0000:  b164 003c 0000 003c 0000 00ff ff1f 1b70
	  0x0010:  f857 ee68 4dfd 4d5f d9bd c709 30ac 8176
	  0x0020:  b36d cc11 3abf 1291 f106 4ede 58f4 6297
	  0x0030:  afc4 39a4 0db9 7aa5 6873 33e8
	RPKI-RTRv65, Error Report PDU (10), length: 66
	  Error code: Unknown (66), Encapsulated PDU length: 37
	    -----encapsulated PDU-----
	[|RPKI-RTR]
	RPKI-RTRv197, Unknown PDU (100), length: 60
	  0x0000:  c564 003c 0000 003c 0000 00ff ff1f 1b70
	  0x0010:  f857 ee68 4dfd 4d5f d9bd c709 30ac 8176
	  0x0020:  b36d cc11 3abf 1291 f106 4ede 61f4 6297
	  0x0030:  afc4 39a4 0db9 7aa5 6873 33e8
	RPKI-RTRv65, Error Report PDU (10), length: 66
	  Error code: Unknown (66), Encapsulated PDU length: 37
	    -----encapsulated PDU-----
	[|RPKI-RTR]
	RPKI-RTRv177, Unknown PDU (100), length: 60
	  0x0000:  b164 003c 0000 003c 0000 00ff ff1f 1b70
	  0x0010:  f857 ee68 4dfd 4d5f d9bd c709 30ac 8176
	  0x0020:  b36d cc11 3abf 1291 f106 4ede 61f4 6297
	  0x0030:  afc4 39a4 0db9 7aa5 6873 33e8
	RPKI-RTRv65, Error Report PDU (10), length: 66
	  Error code: Unknown (66), Encapsulated PDU length: 100
	  Error text: ^@^@^@M-^?M-^?^_^[pM-xWM-nhMM-}M_M-YM-=M-G^I0M-,M-^AvM-3mM-L^Q:M-?^RM-^QM-q^FNM-^aM-tbM-^WM-/M-D9M-$^MM-9zM-%hs3M-hA^J^@B^@^@^@B^@^@^@%M-Dz^HM-i^RM-^DM-5M-^\M->0H^H^@E^P^@4M-}&@^@>^F
	RPKI-RTRv115, Error Report PDU (10), length: 66
	[|RPKI-RTR]
	RPKI-RTRv177, Unknown PDU (100), length: 60
	  0x0000:  b164 003c 0000 003c 0000 00ff ff1f 1b70
	  0x0010:  f857 ee68 4dfd 4d5f d9bd c709 30ac 8176
	  0x0020:  b36d cc11 3abf 1291 f106 4ede 61f4 6297
	  0x0030:  afc4 39a4 0db9 7aa5 6873 33e8
	RPKI-RTRv65, Error Report PDU (10), length: 66
	  Error code: Unknown (66), Encapsulated PDU length: 80
	  Error text: M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-CM-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9M-9^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^V^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J
	[|RPKI-RTR]
	RPKI-RTRv177, Unknown PDU (100), length: 60
	  0x0000:  b164 003c 0000 003c 0000 00ff ff1f 1b70
	  0x0010:  f857 ee68 4dfd 4d5f d9bd c709 30ac 8176
	  0x0020:  b36d cc11 3abf 1291 f106 4ede 58f4 6297
	  0x0030:  afc4 39a4 0db9 7aa5 6873 33e8
	RPKI-RTRv65, Error Report PDU (10), length: 66
	  Error code: Unknown (66), Encapsulated PDU length: 37
	    -----encapsulated PDU-----
	[|RPKI-RTR]
	RPKI-RTRv197, Unknown PDU (100), length: 60
	  0x0000:  c564 003c 0000 003c 0000 00ff ff1f 1b70
	  0x0010:  f857 ee68 4dfd 4d5f d9bd c709 30ac 8176
	  0x0020:  b36d cc11 3abf 1291 f106 4ede 61f4 6297
	  0x0030:  afc4 39a4 0db9 7aa5 6873 33e8
	RPKI-RTRv65, Error Report PDU (10), length: 66
	  Error code: Unknown (66), Encapsulated PDU length: 37
	    -----encapsulated PDU-----
	[|RPKI-RTR]
	RPKI-RTRv177, Unknown PDU (100), length: 60
	  0x0000:  b164 003c 0000 003c 0000 00ff ff1f 1b70
	  0x0010:  f857 ee68 4dfd 4d5f d9bd c709 30ac 8176
	  0x0020:  b36d cc11 3abf 1291 f106 4ede 61f4 6297
	  0x0030:  afc4 39a4 0db9 7aa5 6873 33e8
	RPKI-RTRv65, Error Report PDU (10), length: 66
	  Error code: Unknown (66), Encapsulated PDU length: 100
	[|RPKI-RTR]
	RPKI-RTRv177, Unknown PDU (100), length: 60
	  0x0000:  b164 003c 0000 003c 0000 00ff ff1f 1b70
	  0x0010:  f857 ee68 4dfd 4d5f d9bd c709 30ac 8176
	  0x0020:  b36d cc11 3abf 1291 f106 4ede 61f4 6297
	  0x0030:  afc4 39a4 0db9 7aa5 6873 33e8
	RPKI-RTRv65, Error Report PDU (10), length: 66
	  Error code: Unknown (66), Encapsulated PDU length: 80
	[|RPKI-RTR]

Fixed code:
    /* Copy of Erroneous PDU (variable, optional) */
    /* Length of Error Text (4 octets in network byte order) */
    /* Arbitrary Text of Error Diagnostic Message (variable, optional) */
static u_int
rpki_rtr_pdu_print (netdissect_options *ndo, const u_char *tptr, const u_int len,
	const u_char recurse, const u_int indent)
    /* Protocol Version */
    ND_TCHECK_8BITS(tptr);
    if (*tptr != 0) {
	/* Skip the rest of the input buffer because even if this is
	 * a well-formed PDU of a future RPKI-Router protocol version
	 * followed by a well-formed PDU of RPKI-Router protocol
	 * version 0, there is no way to know exactly how to skip the
	 * current PDU.
	 */
	ND_PRINT((ndo, "%sRPKI-RTRv%u (unknown)", indent_string(8), *tptr));
	return len;
    }
    if (len < sizeof(rpki_rtr_pdu)) {
	ND_PRINT((ndo, "(%u bytes is too few to decode)", len));
	goto invalid;
    }
    ND_TCHECK2(*tptr, sizeof(rpki_rtr_pdu));
    /* Do not check bounds with pdu_len yet, do it in the case blocks
     * below to make it possible to decode at least the beginning of
     * a truncated Error Report PDU or a truncated encapsulated PDU.
     */
    if (pdu_len < sizeof(rpki_rtr_pdu) || pdu_len > len)
	goto invalid;
	if (pdu_len != sizeof(rpki_rtr_pdu) + 4)
	    goto invalid;
	ND_TCHECK2(*tptr, pdu_len);
	if (pdu_len != sizeof(rpki_rtr_pdu))
	    goto invalid;
	/* no additional boundary to check */
	if (pdu_len != sizeof(rpki_rtr_pdu))
	    goto invalid;
	/* no additional boundary to check */
	    if (pdu_len != sizeof(rpki_rtr_pdu) + 12)
		goto invalid;
	    ND_TCHECK2(*tptr, pdu_len);
	    if (pdu_len != sizeof(rpki_rtr_pdu) + 24)
		goto invalid;
	    ND_TCHECK2(*tptr, pdu_len);
	    tlen = sizeof(rpki_rtr_pdu);
	    /* Do not test for the "Length of Error Text" data element yet. */
	    if (pdu_len < tlen + 4)
		goto invalid;
	    ND_TCHECK2(*tptr, tlen + 4);
	    /* Safe up to and including the "Length of Encapsulated PDU"
	     * data element, more data elements may be present.
	     */
	    tlen += 4;
	    if (encapsulated_pdu_length) {
		/* Section 5.10 of RFC 6810 says:
		 * "An Error Report PDU MUST NOT be sent for an Error Report PDU."
		 *
		 * However, as far as the protocol encoding goes Error Report PDUs can
		 * happen to be nested in each other, however many times, in which case
		 * the decoder should still print such semantically incorrect PDUs.
		 *
		 * That said, "the Erroneous PDU field MAY be truncated" (ibid), thus
		 * to keep things simple this implementation decodes only the two
		 * outermost layers of PDUs and makes bounds checks in the outer and
		 * the inner PDU independently.
		 */
		if (pdu_len < tlen + encapsulated_pdu_length)
		    goto invalid;
		if (! recurse) {
		    ND_TCHECK2(*tptr, tlen + encapsulated_pdu_length);
		}
		else {
		    ND_PRINT((ndo, "%s-----encapsulated PDU-----", indent_string(indent+4)));
		    rpki_rtr_pdu_print(ndo, tptr + tlen,
			encapsulated_pdu_length, 0, indent + 2);
		}
		tlen += encapsulated_pdu_length;
	    if (pdu_len < tlen + 4)
		goto invalid;
	    ND_TCHECK2(*tptr, tlen + 4);
	    /* Safe up to and including the "Length of Error Text" data element,
	     * one more data element may be present.
	     */
	    text_length = EXTRACT_32BITS(tptr + tlen);
	    tlen += 4;

	    if (text_length) {
		if (pdu_len < tlen + text_length)
		    goto invalid;
		/* fn_printn() makes the bounds check */
		if (fn_printn(ndo, tptr + tlen, text_length, ndo->ndo_snapend))
	ND_TCHECK2(*tptr, pdu_len);
    return pdu_len;
invalid:
    ND_PRINT((ndo, "%s", istr));
    ND_TCHECK2(*tptr, len);
    return len;
    ND_PRINT((ndo, "\n\t%s", tstr));
    return len;
    while (len) {
	u_int pdu_len = rpki_rtr_pdu_print(ndo, pptr, len, 1, 8);
	len -= pdu_len;
	pptr += pdu_len;
rpki-rtr-oob		rpki-rtr-oob.pcap	rpki-rtr-oob.out	-v -c1
	RPKI-RTRv177 (unknown)
	RPKI-RTRv177 (unknown)
	RPKI-RTRv177 (unknown)
	RPKI-RTRv177 (unknown)
	RPKI-RTRv197 (unknown)
	RPKI-RTRv177 (unknown)
	RPKI-RTRv177 (unknown)
	RPKI-RTRv177 (unknown)
	RPKI-RTRv197 (unknown)
	RPKI-RTRv177 (unknown)
	RPKI-RTRv177 (unknown)
IP truncated-ip - 22 bytes missing! (tos 0x0, ttl 254, id 13327, offset 0, flags [+, DF, rsvd], proto TCP (6), length 62, bad cksum 8e7f (->c283)!)
    19.128.128.20.323 > 76.19.6.127.49600: Flags [none], seq 2684354563:2684354585, win 28672, length 22
	RPKI-RTRv171 (unknown)