gossmap: don't crash if we hit a zero-length record.

We have a report of this happening under ZFS. We cannot do much if this really is a problem where we can't read back what we write, but this avoids the immediate crash. Fixes: ElementsProject#7971 Signed-off-by: Rusty Russell <[email protected]> Changelog-Fixed: gossmap: occasional crash (at least on ZFS) reading gossip_store.
rustyrussell · Feb 6, 2025 · 1f45ef8 · 1f45ef8
1 parent 1f26e34
commit 1f45ef8
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/common/gossmap.c b/common/gossmap.c
@@ -701,6 +701,10 @@ static bool map_catchup(struct gossmap *map, bool *changed)
 		if (map->map_end + reclen > map->map_size)
 			break;
 
+		/* FIXME: In corruption, we can see zeroes here: don't crash. */
+		if (be16_to_cpu(ghdr.len) < sizeof(be16))
+			break;
+
 		off = map->map_end + sizeof(ghdr);
 		type = map_be16(map, off);
 		if (type == WIRE_CHANNEL_ANNOUNCEMENT) {