From 4589352dac3ae111c7621298cf231742209efd9b Mon Sep 17 00:00:00 2001 From: Bill Fenner Date: Fri, 25 Nov 2022 08:41:24 -0800 Subject: [PATCH ] snmp_agent: disallow SET with NULL varbind Upstream-Status: Backport [https://github.com/net-snmp/net-snmp/commit/be804106fd0771a7d05236cff36e199af077af57] CVE: CVE-2022-44792 & CVE-2022-44793 Signed-off-by: Hitendra Prajapati --- agent/snmp_agent.c | 32 +++++++++++++++++++ apps/snmpset.c | 1 + .../default/T0142snmpv2csetnull_simple | 31 ++++++++++++++++++ 3 files changed, 64 insertions(+) create mode 100644 testing/fulltests/default/T0142snmpv2csetnull_simple diff --git a/agent/snmp_agent.c b/agent/snmp_agent.c index 3376357..f51c252 100644 --- a/agent/snmp_agent.c +++ b/agent/snmp_agent.c @@ -3719,12 +3719,44 @@ netsnmp_handle_request(netsnmp_agent_session *asp, int status) return 1; } +static int +check_set_pdu_for_null_varbind(netsnmp_agent_session *asp) +{ + int i; + netsnmp_variable_list *v = NULL; + + for (i = 1, v = asp->pdu->variables; v != NULL; i++, v = v->next_variable) { + if (v->type == ASN_NULL) { + /* + * Protect SET implementations that do not protect themselves + * against wrong type. + */ + DEBUGMSGTL(("snmp_agent", "disallowing SET with NULL var for varbind %d\n", i)); + asp->index = i; + return SNMP_ERR_WRONGTYPE; + } + } + return SNMP_ERR_NOERROR; +} + int handle_pdu(netsnmp_agent_session *asp) { int status, inclusives = 0; netsnmp_variable_list *v = NULL; +#ifndef NETSNMP_NO_WRITE_SUPPORT + /* + * Check for ASN_NULL in SET request + */ + if (asp->pdu->command == SNMP_MSG_SET) { + status = check_set_pdu_for_null_varbind(asp); + if (status != SNMP_ERR_NOERROR) { + return status; + } + } +#endif /* NETSNMP_NO_WRITE_SUPPORT */ + /* * for illegal requests, mark all nodes as ASN_NULL */ diff --git a/apps/snmpset.c b/apps/snmpset.c index 50f33db..387a51d 100644 --- a/apps/snmpset.c +++ b/apps/snmpset.c @@ -182,6 +182,7 @@ main(int argc, char *argv[]) case 'x': case 'd': case 'b': + case 'n': /* undocumented */ #ifdef NETSNMP_WITH_OPAQUE_SPECIAL_TYPES case 'I': case 'U': diff --git a/testing/fulltests/default/T0142snmpv2csetnull_simple b/testing/fulltests/default/T0142snmpv2csetnull_simple new file mode 100644 index 0000000..0f1b8f3 --- /dev/null +++ b/testing/fulltests/default/T0142snmpv2csetnull_simple @@ -0,0 +1,31 @@ +#!/bin/sh + +. ../support/simple_eval_tools.sh + +HEADER SNMPv2c set of system.sysContact.0 with NULL varbind + +SKIPIF NETSNMP_DISABLE_SET_SUPPORT +SKIPIF NETSNMP_NO_WRITE_SUPPORT +SKIPIF NETSNMP_DISABLE_SNMPV2C +SKIPIFNOT USING_MIBII_SYSTEM_MIB_MODULE + +# +# Begin test +# + +# standard V2C configuration: testcomunnity +snmp_write_access='all' +. ./Sv2cconfig +STARTAGENT + +CAPTURE "snmpget -On $SNMP_FLAGS -c testcommunity -v 2c $SNMP_TRANSPORT_SPEC:$SNMP_TEST_DEST$SNMP_SNMPD_PORT .1.3.6.1.2.1.1.4.0" + +CHECK ".1.3.6.1.2.1.1.4.0 = STRING:" + +CAPTURE "snmpset -On $SNMP_FLAGS -c testcommunity -v 2c $SNMP_TRANSPORT_SPEC:$SNMP_TEST_DEST$SNMP_SNMPD_PORT .1.3.6.1.2.1.1.4.0 n x" + +CHECK "Reason: wrongType" + +STOPAGENT + +FINISHED -- 2.25.1