interface: fix if_index is not parsed correctly

Replace probed_ifaces[i] with ifs.

In SDC 2020 SMB3 Virtual IO Lab,
run Windows Protocol Test Suite to test FileServer multichannel test cases.
Samba server has 2 virtual interfaces for VPN connection:
> name=tun2001, ip/mask=192.168.144.9/22
> name=tun2002, ip/mask=192.168.144.10/22
test suite client can ping these 2 ip addresses and browse shares.
Then client try to use IOCTL FSCTL_QUERY_NETWORK_INTERFACE_INFO to get the
virtual ip addresses of samba server, but samba server responded it
without the virtual ip addresses. My VPN setup is point-to-point and the
virtual interfaces 'tun2001' & 'tun2002' are without flag IFF_BROADCAST.
So edit smb.conf and add
"interfaces = ${virtual_ip}/${mask_length};if_index=${id}", like this:
> interfaces = eth4 eth8 eth11 eth10 qvs0 "192.168.144.9/22;if_index=50" "192.168.144.10/22;if_index=51"
then samba server IOCTL response could return the virtual ip addresses,
but found a issue:
the interface index of virtual ip addresses is always 4294967295
(0xFFFFFFFF, -1).

Quote Metze: https://gitlab.com/samba-team/devel/samba/-/commit/6cadb55d975a6348a417caed8b3258f5be2acba4#note_419181789
This looks good, I think that also explains
the possible memory corruption/crash I mentioned in the bug report.
As 'i' is most likely the same as 'total_probed' and
probed_ifaces[i] is not valid, so we overwrite unrelated memory.
Later I see 'realloc(): invalid pointer' and this backtrace:
  BACKTRACE:
   #0 log_stack_trace + 0x29 [ip=0x7f2f1b6fffa9] [sp=0x7ffcd0ab53e0]
   #1 smb_panic + 0x11 [ip=0x7f2f1b700301] [sp=0x7ffcd0ab5d10]
   #2 sig_fault + 0x54 [ip=0x7f2f1b7004f4] [sp=0x7ffcd0ab5e20]
   #3 funlockfile + 0x50 [ip=0x7f2f17ce6dd0] [sp=0x7ffcd0ab5ec0]
   #4 gsignal + 0x10f [ip=0x7f2f1794970f] [sp=0x7ffcd0ab6b90]
   #5 abort + 0x127 [ip=0x7f2f17933b25] [sp=0x7ffcd0ab6cb0]
   #6 __libc_message + 0x297 [ip=0x7f2f1798c897] [sp=0x7ffcd0ab6de0]
   #7 malloc_printerr + 0x1c [ip=0x7f2f17992fdc] [sp=0x7ffcd0ab6ef0]
   #8 realloc + 0x23a [ip=0x7f2f17997f6a] [sp=0x7ffcd0ab6f00]
   #9 _talloc_realloc + 0xee [ip=0x7f2f1a365d2e] [sp=0x7ffcd0ab6f50]
   #10 messaging_filtered_read_send + 0x18c [ip=0x7f2f1a10f54c] [sp=0x7ffcd0ab6fb0]
   #11 messaging_read_send + 0x55 [ip=0x7f2f1a10f705] [sp=0x7ffcd0ab7000]
   #12 smb2srv_session_table_init + 0x83 [ip=0x7f2f1b3a6cd3] [sp=0x7ffcd0ab7040]
   #13 smbXsrv_connection_init_tables + 0x2d [ip=0x7f2f1b373f4d] [sp=0x7ffcd0ab7060]
   #14 smbd_smb2_request_process_negprot + 0x827 [ip=0x7f2f1b38cb47] [sp=0x7ffcd0ab7080]
   #15 smbd_smb2_request_dispatch + 0x19db [ip=0x7f2f1b38921b] [sp=0x7ffcd0ab71d0]
   #16 smbd_smb2_process_negprot + 0x298 [ip=0x7f2f1b38bb38] [sp=0x7ffcd0ab7260]
   #17 process_smb + 0x2ca [ip=0x7f2f1b37537a] [sp=0x7ffcd0ab72b0]
   #18 smbd_server_connection_read_handler + 0xd0 [ip=0x7f2f1b376420] [sp=0x7ffcd0ab7350]

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14514

Signed-off-by: Jones Syue <jonessyue@qnap.com>
Reviewed-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>

source3/lib/interface.c

@@ -618,7 +618,7 @@ static void interpret_interface(char *token)
 	ifs.netmask = ss_mask;
 	ifs.bcast = ss_bcast;
 	if (if_index_set) {
-		probed_ifaces[i].if_index = if_index;
+		ifs.if_index = if_index;
 	}
 	if (speed_set) {
 		ifs.linkspeed = speed;