[libsmi] [PATCH] Memory leak in smidump netsnmp output

31 May 2006

smidump generates netsnmp wrappers that appear to contain a small memory
leak if snmp_open() fails. For example...
...
int powernet_mib_mgr_get_upsPhaseResetValues(struct snmp_session *s, upsPhaseResetValues_t **upsPhaseResetValues)
{
    struct snmp_session *peer;
    struct snmp_pdu *request, *response;
    struct variable_list *vars;
    int status;
request = snmp_pdu_create(SNMP_MSG_GETNEXT);

request is allocated...
...
snmp_add_null_var(request, upsPhaseResetMaxMinValues, sizeof(upsPhaseResetMaxMinValues)/sizeof(oid));

peer = snmp_open(s);
if (!peer) {
    return -1;

...and here we potentially return without freeing it.
...
}

status = snmp_synch_response(peer, request, &response);

snmp_synch_response() frees request in all cases, so there are no leaks
after this point.
...
if (status != STAT_SUCCESS) {
    if (response) snmp_free_pdu(response);
    snmp_close(peer);
    return -2;
}


...
My knowledge of netsnmp is limited, but I believe the analysis above 
is correct. Below is a small patch to solve the problem.
--Adam

--- libsmi-0.4.5/tools/dump-netsnmp.c	2005-11-25 04:13:58.000000000 -0500
+++ libsmi-0.4.5/tools/dump-netsnmp.new.c	2006-05-30 18:30:36.000000000 -0400
@@ -1149,6 +1149,7 @@
        "\n"
        "    peer = snmp_open(s);\n"
        "    if (!peer) {\n"
+	    "        snmp_free_pdu(request);\n"
        "        return -1;\n"
        "    }\n"
        "\n"

    

[libsmi] [PATCH] Memory leak in smidump netsnmp output

Adam Kropelin