nat: Fix timeslot range in 'show bsc mgcp' VTY command

Currently the inner loop in show_bsc_mgcp iterates of the timeslot
interval [0, 31]. Timeslot 0 is not valid, which causes
mgcp_timeslot_to_endpoint to generate a corresponding warning and to
return an invalid endp value. That value causes an out-of-bound
read access, possibly hitting unallocated memory.

This patch fixes the loop range by starting with timeslot 1.

Note that this does not prevent mgcp_timeslot_to_endpoint from
returning an invalid endpoint index when called with arguments not
within its domain.

Addresses:
<000b> ../../include/openbsc/mgcp.h:250 Timeslot should not be 0
[...]
    vty=0xb4203db0, argc=1, argv=0xbfffebb0) at bsc_nat_vty.c:256
        max = 1
        con = 0xb4a004f0
        i = 0
        j = 0
[...]
==15700== ERROR: AddressSanitizer: heap-use-after-free on address
0xb520be4f at pc 0x8062a42 bp 0xbfffeb18 sp 0xbfffeb0c

Sponsored-by: On-Waves ehf

0 files changed, 0 insertions, 0 deletions