1228893 - snmpd segfaults on reload with multiple 'exec' entry

commit 54290bede338164ca65a3eed224fa5040d7dd857

Author: Niels Baggesen <nba@users.sourceforge.net>

Date:   Fri Oct 26 07:50:11 2012 +0200

    Better cleanup of "exec" config to avoid crash during reload of config

diff --git a/agent/mibgroup/agent/extend.c b/agent/mibgroup/agent/extend.c

index 68a11e2..9cb641c 100644

--- a/agent/mibgroup/agent/extend.c

+++ b/agent/mibgroup/agent/extend.c

@@ -34,7 +34,7 @@ typedef struct extend_registration_block_s {

     size_t              oid_len;

     long                num_entries;

     netsnmp_extend     *ehead;

-    netsnmp_handler_registration       *reg[3];

+    netsnmp_handler_registration       *reg[4];

     struct extend_registration_block_s *next;

 } extend_registration_block;

 extend_registration_block *ereg_head = NULL;

@@ -222,10 +222,13 @@ _register_extend( oid *base, size_t len )

     rc = netsnmp_register_watched_scalar2( reg, winfo );

     if (rc != SNMPERR_SUCCESS)

         goto bail;

+    eptr->reg[3] = reg;

     return eptr;

 bail:

+    if (eptr->reg[3])

+        netsnmp_unregister_handler(eptr->reg[3]);

     if (eptr->reg[2])

         netsnmp_unregister_handler(eptr->reg[2]);

     if (eptr->reg[1])

@@ -267,6 +270,7 @@ extend_clear_callback(int majorID, int minorID,

         netsnmp_unregister_handler( eptr->reg[0] );

         netsnmp_unregister_handler( eptr->reg[1] );

         netsnmp_unregister_handler( eptr->reg[2] );

+        netsnmp_unregister_handler( eptr->reg[3] );

         SNMP_FREE(eptr);

     }

     ereg_head = NULL;

@@ -550,6 +554,10 @@ extend_parse_config(const char *token, char *cptr)

     }

     eptr      = _register_extend( oid_buf, oid_len );

+    if (!eptr) {

+        snmp_log(LOG_ERR, "Failed to register extend entry '%s' - possibly duplicate name.\n", exec_name );

+        return;

+    }

     extension = _new_extension( exec_name, flags, eptr );

     if (extension) {

         extension->command  = strdup( exec_command );