[patch] The patch for the problem

net-snmp-5.4.2.1.infinite-fix-loop.patch (text/plain), 1.89 KB, created by Doug on 2009-01-27 17:03:37 UTC

--- snmplib/snmp_client.c.original	2009-01-26 12:53:28.000000000 -0500
+++ snmplib/snmp_client.c	2009-01-26 12:51:18.000000000 -0500
@@ -580,8 +580,9 @@
  * The command is set to the input command and the reqid, errstat, and
  * errindex are set to default values.
  * If the error status didn't indicate an error, the error index didn't
- * indicate a variable, the pdu wasn't a get response message, or there
- * would be no remaining variables, this function will return 0.
+ * indicate a variable, the pdu wasn't a get response message, there
+ * would be no remaining variables, or the marked variable was not
+ * present in the initial request, this function will return 0.
  * If everything was successful, a pointer to the fixed cloned pdu will
  * be returned.
  */
@@ -590,10 +591,24 @@
 {
     netsnmp_pdu    *newpdu;
 
-    if ((pdu->command != SNMP_MSG_RESPONSE)
+    if (
+        // We're only going to fix a PDU if it was a *response* to us.
+        (pdu->command != SNMP_MSG_RESPONSE)
+        // We're only going to fix a PDU that had an error.
         || (pdu->errstat == SNMP_ERR_NOERROR)
+        // We're only going to fix a PDU that has varbinds.
         || (0 == pdu->variables)
-        || (pdu->errindex <= 0)) {
+        // We're only going to fix a PDU with a positive error-index.
+        || (pdu->errindex <= 0)
+        // We're only going to fix a PDU if we can actually remove
+        // the varbind that was listed as being "bad".  If the number
+        // of varbinds is *less* than the error-index value, then
+        // we can't really do anything except simply resend the PDU
+        // and hope for a better response, and that's not a good
+        // thing to do; previously, this had led to infinite loops
+        // of send, receive, and resend.
+        || (pdu->errindex > snmp_varbind_len(pdu))
+    ) {
         return 0;               /* pre-condition tests fail */
     }