bgpd: fix table deleted before thread

Temporal fix

Thread 2.1 "bgpd" received signal SIGSEGV, Segmentation fault.
0x00007ffff7b14180 in route_top (table=0x0) at lib/table.c:401
401		if (table->top == NULL)
(gdb) bt
\#0  0x00007ffff7b14180 in route_top (table=0x0) at lib/table.c:401
\#1  0x0000555555657286 in bgp_table_top (table=0x55555629c440) at ./bgpd/bgp_table.h:203
\#2  0x0000555555666dd0 in bgp_soft_reconfig_table_flag (srta=0x55555bc68fd0, flag=false) at bgpd/bgp_route.c:4669
\#3  0x0000555555666f5e in bgp_soft_reconfig_table_thread_cancel (nsrta=0x0, bgp=0x5555562767a0) at bgpd/bgp_route.c:4698
\FRRouting#4  0x00005555556e9463 in bgp_delete (bgp=0x5555562767a0) at bgpd/bgpd.c:3482
\FRRouting#5  0x00005555556f9ae5 in bgp_router_destroy (args=0x7fffffff6b90) at bgpd/bgp_nb_config.c:176
\FRRouting#6  0x00007ffff7ad985d in nb_callback_destroy (context=0x7fffffff7180, nb_node=0x555555c0c580, event=NB_EV_APPLY, dnode=0x5555563cdbf0, errmsg=0x7fffffff7190 "", errmsg_len=8192) at lib/northbound.c:970
\FRRouting#7  0x00007ffff7ada17a in nb_callback_configuration (context=0x7fffffff7180, event=NB_EV_APPLY, change=0x55555d5aa560, errmsg=0x7fffffff7190 "", errmsg_len=8192) at lib/northbound.c:1195
\FRRouting#8  0x00007ffff7ada564 in nb_transaction_process (event=NB_EV_APPLY, transaction=0x55556a6ed510, errmsg=0x7fffffff7190 "", errmsg_len=8192) at lib/northbound.c:1312
\FRRouting#9  0x00007ffff7ad900b in nb_candidate_commit_apply (transaction=0x55556a6ed510, save_transaction=true, transaction_id=0x0, errmsg=0x7fffffff7190 "", errmsg_len=8192) at lib/northbound.c:745
\FRRouting#10 0x00007ffff7ad912e in nb_candidate_commit (context=0x7fffffff7180, candidate=0x555555bddd00, save_transaction=true, comment=0x0, transaction_id=0x0, errmsg=0x7fffffff7190 "", errmsg_len=8192) at lib/northbound.c:777
\FRRouting#11 0x00007ffff7ae0249 in nb_cli_classic_commit (vty=0x555557b62790) at lib/northbound_cli.c:64
\FRRouting#12 0x00007ffff7ae0cce in nb_cli_apply_changes (vty=0x555557b62790, xpath_base_fmt=0x7fffffffb730 "/frr-routing:routing/control-plane-protocols/control-plane-protocol[type='frr-bgp:bgp'][name='bgp'][vrf='default']/frr-bgp:bgp") at lib/northbound_cli.c:281
\FRRouting#13 0x00005555556a01e6 in no_router_bgp (self=0x555555a28140 <no_router_bgp_cmd>, vty=0x555557b62790, argc=3, argv=0x555560be1bd0) at bgpd/bgp_vty.c:1466
\FRRouting#14 0x00007ffff7a90ebc in cmd_execute_command_real (vline=0x55556635c140, filter=FILTER_RELAXED, vty=0x555557b62790, cmd=0x0) at lib/command.c:938
\FRRouting#15 0x00007ffff7a91031 in cmd_execute_command (vline=0x55556635c140, vty=0x555557b62790, cmd=0x0, vtysh=0) at lib/command.c:997
\FRRouting#16 0x00007ffff7a91586 in cmd_execute (vty=0x555557b62790, cmd=0x555557b68f20 "no router bgp", matched=0x0, vtysh=0) at lib/command.c:1162
\FRRouting#17 0x00007ffff7b228f9 in vty_command (vty=0x555557b62790, buf=0x555557b68f20 "no router bgp") at lib/vty.c:517
\FRRouting#18 0x00007ffff7b2465b in vty_execute (vty=0x555557b62790) at lib/vty.c:1282
\FRRouting#19 0x00007ffff7b2656e in vtysh_read (thread=0x7fffffffe2e0) at lib/vty.c:2120
\FRRouting#20 0x00007ffff7b1bd23 in thread_call (thread=0x7fffffffe2e0) at lib/thread.c:1681
\FRRouting#21 0x00007ffff7ac7fc2 in frr_run (master=0x555555a6aab0) at lib/libfrr.c:1110
\FRRouting#22 0x00005555555d88b2 in main (argc=4, argv=0x7fffffffe518) at bgpd/bgp_main.c:523

Signed-off-by: Louis Scalbert <louis.scalbert@6wind.com>

bgpd/bgp_route.c

@@ -4666,6 +4666,10 @@ static void bgp_soft_reconfig_table_flag(struct soft_reconfig_table *srta, bool
 	if (!table)
 		table = srta->peer->bgp->rib[srta->afi][srta->safi];
 
+	/* table is already destroyed. Memory leak to fix*/
+	if (!table)
+		return;
+
 	for (dest = bgp_table_top(table); dest; dest = bgp_route_next(dest)) {
 		for (ain = dest->adj_in; ain; ain = ain->next) {
 			if (ain->peer != srta->peer)