From 30ed5b1cc6aa0efe6ac099b66d33d46c7c0c6b47 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn-Egil=20Dahlberg?= Date: Tue, 7 Apr 2015 12:58:15 +0200 Subject: erts: Fix deep colliding hash values in maps:from_list/1 Reported-by: Jesper Louis Andersen --- erts/emulator/beam/erl_map.c | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) (limited to 'erts/emulator/beam/erl_map.c') diff --git a/erts/emulator/beam/erl_map.c b/erts/emulator/beam/erl_map.c index 20a17bcd24..3bb3622194 100644 --- a/erts/emulator/beam/erl_map.c +++ b/erts/emulator/beam/erl_map.c @@ -679,7 +679,35 @@ static Eterm hashmap_from_chunked_array(ErtsHeapFactory *factory, hxnode_t *hxns DECLARE_ESTACK(stack); Eterm res = NIL, *hp = NULL, *nhp; - ASSERT(n > 1); + + /* if we get here with only one element then + * we have eight levels of collisions + */ + + if (n == 1) { + res = hxns[0].val; + v = hxns[0].hx; + for (d = 7; d > 0; d--) { + slot = maskval(v,d); + hp = erts_produce_heap(factory, HAMT_NODE_BITMAP_SZ(1), HALLOC_EXTRA); + hp[0] = MAP_HEADER_HAMT_NODE_BITMAP(1 << slot); + hp[1] = res; + res = make_hashmap(hp); + } + + slot = maskval(v,0); + hp = erts_produce_heap(factory, (is_root ? 3 : 2), 0); + + if (is_root) { + hp[0] = MAP_HEADER_HAMT_HEAD_BITMAP(1 << slot); + hp[1] = size; + hp[2] = res; + } else { + hp[0] = MAP_HEADER_HAMT_NODE_BITMAP(1 << slot); + hp[1] = res; + } + return make_hashmap(hp); + } /* push initial nodes on the stack, * this is the starting depth */ -- cgit v1.2.3