bgpd/security: debug print of received NOTIFY data can over-read msg array

Security issue: Quagga-2018-1550
See: https://www.quagga.net/security/Quagga-2018-1550.txt

* bgpd/bgp_debug.c: (struct message) Nearly every one of the NOTIFY
  code/subcode message arrays has their corresponding size variables off
  by one, as most have 1 as first index.

  This means (bgp_notify_print) can cause mes_lookup to overread the (struct
  message) by 1 pointer value if given an unknown index.

  Fix the bgp_notify_..._msg_max variables to use the compiler to calculate
  the correct sizes.

bgpd/bgp_debug.c

@@ -29,6 +29,7 @@ Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 #include "log.h"
 #include "sockunion.h"
 #include "filter.h"
+#include "memory.h"
 
 #include "bgpd/bgpd.h"
 #include "bgpd/bgp_aspath.h"
@@ -73,7 +74,8 @@ const struct message bgp_status_msg[] =
   { Clearing,    "Clearing"    },
   { Deleted,     "Deleted"     },
 };
-const int bgp_status_msg_max = BGP_STATUS_MAX;
+#define BGP_DEBUG_MSG_MAX(msg) const int msg ## _max = array_size (msg)
+BGP_DEBUG_MSG_MAX (bgp_status_msg);
 
 /* BGP message type string. */
 const char *bgp_type_str[] =
@@ -84,7 +86,8 @@ const char *bgp_type_str[] =
   "NOTIFICATION",
   "KEEPALIVE",
   "ROUTE-REFRESH",
-  "CAPABILITY"
+  "CAPABILITY",
+  NULL,
 };
 
 /* message for BGP-4 Notify */
@@ -98,15 +101,15 @@ static const struct message bgp_notify_msg[] =
   { BGP_NOTIFY_CEASE, "Cease"},
   { BGP_NOTIFY_CAPABILITY_ERR, "CAPABILITY Message Error"},
 };
-static const int bgp_notify_msg_max = BGP_NOTIFY_MAX;
+BGP_DEBUG_MSG_MAX (bgp_notify_msg);
 
 static const struct message bgp_notify_head_msg[] = 
 {
   { BGP_NOTIFY_HEADER_NOT_SYNC, "/Connection Not Synchronized"},
   { BGP_NOTIFY_HEADER_BAD_MESLEN, "/Bad Message Length"},
-  { BGP_NOTIFY_HEADER_BAD_MESTYPE, "/Bad Message Type"}
+  { BGP_NOTIFY_HEADER_BAD_MESTYPE, "/Bad Message Type"},
 };
-static const int bgp_notify_head_msg_max = BGP_NOTIFY_HEADER_MAX;
+BGP_DEBUG_MSG_MAX (bgp_notify_head_msg);
 
 static const struct message bgp_notify_open_msg[] = 
 {
@@ -119,7 +122,7 @@ static const struct message bgp_notify_open_msg[] =
   { BGP_NOTIFY_OPEN_UNACEP_HOLDTIME, "/Unacceptable Hold Time"}, 
   { BGP_NOTIFY_OPEN_UNSUP_CAPBL, "/Unsupported Capability"},
 };
-static const int bgp_notify_open_msg_max = BGP_NOTIFY_OPEN_MAX;
+BGP_DEBUG_MSG_MAX (bgp_notify_open_msg);
 
 static const struct message bgp_notify_update_msg[] = 
 {
@@ -136,7 +139,7 @@ static const struct message bgp_notify_update_msg[] =
   { BGP_NOTIFY_UPDATE_INVAL_NETWORK, "/Invalid Network Field"},
   { BGP_NOTIFY_UPDATE_MAL_AS_PATH, "/Malformed AS_PATH"},
 };
-static const int bgp_notify_update_msg_max = BGP_NOTIFY_UPDATE_MAX;
+BGP_DEBUG_MSG_MAX (bgp_notify_update_msg);
 
 static const struct message bgp_notify_cease_msg[] =
 {
@@ -150,7 +153,7 @@ static const struct message bgp_notify_cease_msg[] =
   { BGP_NOTIFY_CEASE_COLLISION_RESOLUTION, "/Connection collision resolution"},
   { BGP_NOTIFY_CEASE_OUT_OF_RESOURCE, "/Out of Resource"},
 };
-static const int bgp_notify_cease_msg_max = BGP_NOTIFY_CEASE_MAX;
+BGP_DEBUG_MSG_MAX (bgp_notify_cease_msg);
 
 static const struct message bgp_notify_capability_msg[] = 
 {
@@ -159,7 +162,7 @@ static const struct message bgp_notify_capability_msg[] =
   { BGP_NOTIFY_CAPABILITY_INVALID_LENGTH, "/Invalid Capability Length"},
   { BGP_NOTIFY_CAPABILITY_MALFORMED_CODE, "/Malformed Capability Value"},
 };
-static const int bgp_notify_capability_msg_max = BGP_NOTIFY_CAPABILITY_MAX;
+BGP_DEBUG_MSG_MAX (bgp_notify_capability_msg);
 
 /* Origin strings. */
 const char *bgp_origin_str[] = {"i","e","?"};