plugins/renepay/test: fix access-after-free.

We cannot carry pointers into the gossmap across localmod addition
or removal.

We didn't notice because the map->chan_arr is not normally resized,
but if we change gossmap.c line 689 to only allocate 1 to start, we see this:

```
VALGRIND=1 valgrind -q --error-exitcode=7 --track-origins=yes --leak-check=full --show-reachable=yes --errors-for-leak-kinds=all plugins/renepay/test/run-mcf > /dev/null
==2349744== Invalid read of size 4
==2349744==    at 0x1788C2: gossmap_chan_scid (gossmap.c:558)
==2349744==    by 0x1872A2: get_chan_extra_half_by_chan (flow.c:346)
==2349744==    by 0x187797: remove_completed_flow (flow.c:488)
==2349744==    by 0x187927: remove_completed_flow_set (flow.c:518)
==2349744==    by 0x18DF4D: main (run-mcf.c:393)
==2349744==  Address 0x4b80f38 is 88 bytes inside a block of size 136 free'd
==2349744==    at 0x4848C63: realloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==2349744==    by 0x173D71: tal_resize_ (tal.c:744)
==2349744==    by 0x177E36: next_free_chan (gossmap.c:336)
==2349744==    by 0x177ED3: new_channel (gossmap.c:351)
==2349744==    by 0x178441: add_channel (gossmap.c:458)
==2349744==    by 0x1798D4: gossmap_apply_localmods (gossmap.c:904)
==2349744==    by 0x18DEDB: main (run-mcf.c:388)
==2349744==  Block was alloc'd at
==2349744==    at 0x4848C63: realloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==2349744==    by 0x173D71: tal_resize_ (tal.c:744)
==2349744==    by 0x177E36: next_free_chan (gossmap.c:336)
==2349744==    by 0x177ED3: new_channel (gossmap.c:351)
==2349744==    by 0x178441: add_channel (gossmap.c:458)
==2349744==    by 0x178B6D: map_catchup (gossmap.c:635)
==2349744==    by 0x178F45: load_gossip_store (gossmap.c:697)
==2349744==    by 0x179D71: gossmap_load (gossmap.c:978)
==2349744==    by 0x18D22F: main (run-mcf.c:295)
```

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2023-08-14 15:33:26 +09:30
parent 4f16f50353
commit aac8905afd

View file

@ -369,6 +369,9 @@ int main(int argc, char *argv[])
assert(amount_msat_eq(ce->half[1].known_min, AMOUNT_MSAT(0)));
assert(amount_msat_eq(ce->half[1].known_max, AMOUNT_MSAT(1000000000)));
/* Clear that */
remove_completed_flow_set(gossmap, chan_extra_map, flows);
// /* Now try adding a local channel scid */
struct short_channel_id scid13;
@ -389,9 +392,6 @@ int main(int argc, char *argv[])
struct gossmap_chan *local_chan = gossmap_find_chan(gossmap, &scid13);
assert(local_chan);
/* Clear that */
remove_completed_flow_set(gossmap, chan_extra_map, flows);
/* The local chans have no "capacity", so set it manually. */
new_chan_extra(chan_extra_map, scid13,
AMOUNT_MSAT(400000000));