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87 lines
3.3 KiB
87 lines
3.3 KiB
2 years ago
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From 92f0fe9e0dc3cf7ab6e8cc94d7962df83d0ddbec Mon Sep 17 00:00:00 2001
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From: Bart Van Assche <bvanassche@acm.org>
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Date: Mon, 4 Jan 2021 12:21:59 -0800
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Subject: [PATCH] libsnmp: Fix asn_parse_nlength()
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Handle length zero correctly.
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Fixes: https://github.com/net-snmp/net-snmp/issues/253
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Fixes: a9850f4445cf ("asn parse: add NULL checks, check length lengths")
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---
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snmplib/asn1.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/snmplib/asn1.c b/snmplib/asn1.c
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index e983500e7..33c272768 100644
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--- a/snmplib/asn1.c
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+++ b/snmplib/asn1.c
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@@ -345,7 +345,7 @@ asn_parse_nlength(u_char *pkt, size_t pkt_len, u_long *data_len)
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* long length; first byte is length of length (after masking high bit)
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*/
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len_len = (int) ((*pkt & ~0x80) + 1);
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- if ((int) pkt_len <= len_len )
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+ if (pkt_len < len_len)
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return NULL; /* still too short for length and data */
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/* now we know we have enough data to parse length */
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From baef04f9c6fe0eb3ac74dd4d26a19264eeaf7fa1 Mon Sep 17 00:00:00 2001
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From: Bart Van Assche <bvanassche@acm.org>
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Date: Mon, 4 Jan 2021 10:00:33 -0800
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Subject: [PATCH] testing/fulltests/unit-tests/T105trap_parse_clib: Add this
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test
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Add a reproducer for the bug fixed by the previous patch.
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---
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.../unit-tests/T105trap_parse_clib.c | 41 +++++++++++++++++++
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1 file changed, 41 insertions(+)
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create mode 100644 testing/fulltests/unit-tests/T105trap_parse_clib.c
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diff --git a/testing/fulltests/unit-tests/T105trap_parse_clib.c b/testing/fulltests/unit-tests/T105trap_parse_clib.c
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new file mode 100644
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index 000000000..5c21ccdc7
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--- /dev/null
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+++ b/testing/fulltests/unit-tests/T105trap_parse_clib.c
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@@ -0,0 +1,41 @@
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+/* HEADER Parsing of an SNMP trap with no varbinds */
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+netsnmp_pdu pdu;
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+int rc;
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+static u_char trap_pdu[] = {
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+ /* Sequence with length of 0x2d = 45 bytes. */
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+ [ 0] = 0x30, [ 1] = 0x82, [ 2] = 0x00, [ 3] = 0x2d,
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+ /* version = INTEGER 0 */
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+ [ 4] = 0x02, [ 5] = 0x01, [ 6] = 0x00,
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+ /* community = public (OCTET STRING 0x70 0x75 0x62 0x6c 0x69 0x63) */
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+ [ 7] = 0x04, [ 8] = 0x06, [ 9] = 0x70, [10] = 0x75,
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+ [11] = 0x62, [12] = 0x6c, [13] = 0x69, [14] = 0x63,
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+ /* SNMP_MSG_TRAP; 32 bytes. */
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+ [15] = 0xa4, [16] = 0x20,
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+ /* enterprise = OBJECT IDENTIFIER .1.3.6.1.6.3.1.1.5 = snmpTraps */
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+ [17] = 0x06, [18] = 0x08,
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+ [19] = 0x2b, [20] = 0x06, [21] = 0x01, [22] = 0x06,
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+ [23] = 0x03, [24] = 0x01, [25] = 0x01, [26] = 0x05,
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+ /* agent-addr = ASN_IPADDRESS 192.168.1.34 */
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+ [27] = 0x40, [28] = 0x04, [29] = 0xc0, [30] = 0xa8,
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+ [31] = 0x01, [32] = 0x22,
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+ /* generic-trap = INTEGER 0 */
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+ [33] = 0x02, [34] = 0x01, [35] = 0x00,
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+ /* specific-trap = INTEGER 0 */
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+ [36] = 0x02, [37] = 0x01, [38] = 0x00,
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+ /* ASN_TIMETICKS 0x117f243a */
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+ [39] = 0x43, [40] = 0x04, [41] = 0x11, [42] = 0x7f,
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+ [43] = 0x24, [44] = 0x3a,
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+ /* varbind list */
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+ [45] = 0x30, [46] = 0x82, [47] = 0x00, [48] = 0x00,
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+};
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+static size_t trap_pdu_length = sizeof(trap_pdu);
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+netsnmp_session session;
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+
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+snmp_set_do_debugging(TRUE);
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+debug_register_tokens("dumpv_recv,dumpv_send,asn,recv");
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+memset(&session, 0, sizeof(session));
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+snmp_sess_init(&session);
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+memset(&pdu, 0, sizeof(pdu));
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+rc = snmp_parse(NULL, &session, &pdu, trap_pdu, trap_pdu_length);
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+
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+OKF((rc == 0), ("Parsing of a trap PDU"));
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