Description of Problem:
When a SMUX client disconnects from snmpd, snmpd crashes.  This did not 
happen with versions of ucd-snmp prior to Red Hat 7.2.

It appears snmpd crashes when it receives the SMUX ClosePDU from the SMUX 
client.



Version-Release number of selected component (if applicable):
(ucd-snmp-4.2.1-7)

How Reproducible:
100%

Steps to Reproduce:
1. send a SMUX ClosePDU while snmpd is running.
2. Here's a code snippet for sending a SMUX ClosePDU:

static void
smux_send_close(int fd, int reason)
{
    u_char outpacket[3], *ptr;

    ptr = outpacket;

    *(ptr++) = (u_char)SMUX_CLOSE;
    *(ptr++) = (u_char)1;
    *ptr = (u_char)(reason & 0xFF);

    if(snmp_get_do_debugging()) 
DEBUGMSGTL (("smux","[smux_close] sending close to fd %d, reason %d\n", 
fd, reason));

    /* send a response back */ 
    if (send (fd, (char *)outpacket, 3, 0) < 0) {
        snmp_log_perror("[smux_snmp_close] send failed");
    }
}

3. 

Actual Results:
snmpd dies

Expected Results:
snmpd should handle it gracefully

Additional Information: